WIP: Relates to #309. Update to Electron v3.1.0

Help...
```
scon @ ~/code/src/paritytech/fether - [luke-309-electron-3] $ yarn; yarn build
yarn install v1.12.3
[1/5] 🔍  Validating package.json...
[2/5] 🔍  Resolving packages...
[3/5] 🚚  Fetching packages...
[4/5] 🔗  Linking dependencies...
warning " > [email protected]" has unmet peer dependency "eslint@>= 4.12.1".
warning " > [email protected]" has unmet peer dependency "prop-types@^15.6.1".
warning " > [email protected]" has unmet peer dependency "react@^16.4.0".
warning "workspace-aggregator-21ff8a39-b153-439b-af1a-2c9e4c694eb4 > fether-react > [email protected]" has unmet peer dependency "prop-types@^15.6.0".
warning "workspace-aggregator-21ff8a39-b153-439b-af1a-2c9e4c694eb4 > fether-react > [email protected]" has unmet peer dependency "prop-types@^15.6.0".
warning "workspace-aggregator-21ff8a39-b153-439b-af1a-2c9e4c694eb4 > fether-ui > [email protected]" has unmet peer dependency "react-dom@>=0.14.0 <= 16".
warning "workspace-aggregator-21ff8a39-b153-439b-af1a-2c9e4c694eb4 > fether-react > @babel/plugin-proposal-decorators > @babel/[email protected]" has unmet peer dependency "@babel/core@^7.0.0-0".
warning "workspace-aggregator-21ff8a39-b153-439b-af1a-2c9e4c694eb4 > fether-react > @babel/[email protected]" has unmet peer dependency "@babel/core@^7.0.0-0".
warning "workspace-aggregator-21ff8a39-b153-439b-af1a-2c9e4c694eb4 > fether-react > @babel/plugin-proposal-decorators > @babel/[email protected]" has unmet peer dependency "@babel/core@^7.0.0".
[5/5] 📃  Building fresh packages...
[6/14] ⠐ @parity/light.js
[2/14] ⠐ @parity/electron
[7/14] ⠐ @parity/light.js-react
[4/14] ⠐ @parity/api
error /Users/scon/code/src/paritytech/fether/node_modules/@parity/light.js: Command failed.
Exit code: 1
Command: yarn build
Arguments:
Directory: /Users/scon/code/src/paritytech/fether/node_modules/@parity/light.js
Output:
yarn run v1.12.3
$ lerna exec yarn build --stream
lerna notice cli v3.10.1
lerna info Executing command in 6 packages: "yarn build"
@parity/abi: $ rimraf lib
@parity/electron: $ rimraf lib
@parity/abi: $ yarn && ./node_modules/.bin/tsc
@parity/electron: $ yarn && ./node_modules/.bin/tsc
@parity/abi: [1/5] Validating package.json...
@parity/abi: [2/5] Resolving packages...
@parity/electron: [1/5] Validating package.json...
@parity/electron: [2/5] Resolving packages...
@parity/abi: [3/5] Fetching packages...
@parity/electron: [3/5] Fetching packages...
@parity/abi: Error: ENFILE: file table overflow, open '/Users/scon/code/src/paritytech/fether/node_modules/@parity/light.js/packages/abi/package.json'
@parity/abi:     at Object.openSync (fs.js:450:3)
@parity/abi:     at Object.readFileSync (fs.js:350:35)
@parity/abi:     at onUnexpectedError (/usr/local/Cellar/yarn/1.12.3/libexec/lib/cli.js:91337:106)
@parity/abi:     at /usr/local/Cellar/yarn/1.12.3/libexec/lib/cli.js:91447:9
@parity/electron: Error: ENFILE: file table overflow, open '/Users/scon/code/src/paritytech/fether/node_modules/@parity/light.js/packages/electron/package.json'
@parity/electron:     at Object.openSync (fs.js:450:3)
@parity/electron:     at Object.readFileSync (fs.js:350:35)
@parity/electron:     at onUnexpectedError (/usr/local/Cellar/yarn/1.12.3/libexec/lib/cli.js:91337:106)
@parity/electron:     at /usr/local/Cellar/yarn/1.12.3/libexec/lib/cli.js:91447:9
@parity/abi: error Command failed with exit code 1.
@parity/abi: info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
lerna ERR! yarn build exited 1 in '@parity/abi'

yarn run v1.12.3
$ lerna run build
lerna notice cli v3.10.1
lerna info Executing command in 3 packages: "yarn run build"
lerna info run Ran npm script 'build' in 'fether-ui' in 4.0s:
$ rimraf lib
$ babel src --out-dir lib
🎉  Successfully compiled 39 files with Babel.
lerna ERR! yarn run build exited 1 in 'fether-react'
lerna ERR! yarn run build stdout:
$ npm-run-all build-*
$ node-sass-chokidar src/ -o src/
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

lerna ERR! yarn run build stderr:
/Users/scon/code/src/paritytech/fether/node_modules/node-sass/lib/binding.js:13
      throw new Error(errors.unsupportedEnvironment());
      ^

Error: Node Sass does not yet support your current environment: OS X 64-bit with Unsupported runtime (67)
For more information on which environments are supported please see:
https://github.com/sass/node-sass/releases/tag/v4.9.0
    at module.exports (/Users/scon/code/src/paritytech/fether/node_modules/node-sass/lib/binding.js:13:13)
    at Object.<anonymous> (/Users/scon/code/src/paritytech/fether/node_modules/node-sass/lib/index.js:14:35)
    at Module._compile (internal/modules/cjs/loader.js:721:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:732:10)
    at Module.load (internal/modules/cjs/loader.js:620:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:560:12)
    at Function.Module._load (internal/modules/cjs/loader.js:552:3)
    at Module.require (internal/modules/cjs/loader.js:657:17)
    at require (internal/modules/cjs/helpers.js:22:18)
    at Object.<anonymous> (/Users/scon/code/src/paritytech/fether/node_modules/node-sass-chokidar/bin/node-sass-chokidar:18:9)
error Command failed with exit code 1.
ERROR: "build-css" exited with 1.
error Command failed with exit code 1.

lerna ERR! yarn run build exited 1 in 'fether-react'
error Command failed with exit code 1.
```