Add dapp-wallet to built-in dapps; load it from fs (#126)

* Add dapp-wallet to built-in dapps; load it locally

* Add dapp-wallet to built-in dapps
* Modify inject.js to cover local dapp name "v1" (not a hash)

* Ignore v1 served by Parity (builtin dapps take precedence)

* Move @parity/dapp-wallet to devDependencies

* Update package-lock.json

* Update dapp-wallet dependency

* Modify inject.js to support v1 in Electron dev mode

* Update dapp-wallet dependency