* Update Send transaction UI so "amount" field can be 0, since some users may want to just send some data (i.e. https://github.com/chainx-org/ChainX/issues/66)
* Set the default amount value to be 0 and not required
* Update Send transaction UI to support "data" field in hex (with 0x prefix)
* Use a hard-coded Gas Limit of 200,000 when user provides hex "data" value
* Remove logic that doesn't make sense (i.e. `else if (amountBn.isZero()) {`)
* Update validation messages
* Add support for Blockscout link when user using Goerli testnet
* Update internationalisation
* Use custom `isHexString` function instead of the ethereumjs-util's version. The ethereumjs-util's version is used by MyCrypto and doesn't work properly.
* Tested on Goerli testnet by creating two accounts, requesting Goerli tokens, running with `--chain goerli` appended to the end (i.e. `"start": "cross-env ELECTRON_START_URL=http://localhost:3000 electron-webpack dev --chain goerli",` in fether/packages/fether-electron/package.json), and sending a transaction with the high gas price, the hex data. For example, for ChainX convert your ChainX Address (UTF8 chars) into Hex code (i.e. copy/paste it at https://www.browserling.com/tools/utf8-to-hex, for example "helloworld" becomes => `\x68\x65\x6c\x6c\x6f\x20\x77\x6f\x72\x6c\x64`, and remove the `\x`, => `68656c6c6f20776f726c64` => then prepend 0x => `0x68656c6c6f20776f726c64` and add that to the "data" field), then send the transaction, and
when the transaction is successful go to the Blockscout link and you'll see under "Raw Input" ("Input Data" on Etherscan) that you can switch between viewing it in UTF8 or Hex, i.e. https://blockscout.com/eth/goerli/tx/0x7eaec61ce7753fd4c80aec4509c49942b53986585e4864e18134806bffb25f10/internal_transactions)
* TODO - update Parity Signer to show "data" field value if it doesn't already

feat: Relates to #360. Only allow import from Parity Signer chain account matching current chain. ETC support (#483)

* feat: Relates to #360. Only allow import from Parity Signer chain account matching current chain. ETC support

* review-fix: Refer to non-Parity chain names in the UI. Add console.error

* review-fix: Do not need to chcek health status before calling chainId RPC of light.js on pages accessed through navigation

* review-fix: Rename function name that matches current chain id with imported chain id of address

* review-fix: Remove unnecessary function

* review-fix: Rename function to accountAlreadyExists

* review-fix: Remove FIXME. See https://github.com/paritytech/fether/pull/483#discussion_r270834847

* review-fix: Refactor to use util functions isEtcChainId, chainIdToString, isNotErc20TokenAddress

* fix: Fix typo in comment

* review-fix: Change wording of parity phrase comment

* review-fix: Do not clear isImport as not account related

* fix: Clear error so error when recover from seed phrase not still shown if then click to recover from QR code

* fix: Rename so signerChainId correctly destructured and not undefined

* review-fix: Remove async/await from clear

* fix: Avoid mapping signer chain id to chain name since too much maintenance with Parity Ethereum

* review-fix: Remove await from createAccountStore

* tests: Add colour to fether-react tests

* refactor: No need to parseInt on the signerChainId

* refactor: Use isNotErc20TokenAddress

* refactor: Use isNotErc20TokenAddress again

* refactor: Add isErc20TokenAddress util so more readable

* fix: Replace valueOf with .eq. Fix so obtain BN from props

* refactor: Combine into single if statement when checking if valid Eth/Etc address

* refactor: Update utils without unnecessary return block

- Add option to import a Parity Signer account. It is then stored in
local storage.

- Send transactions with Parity Signer accounts

- Refactor sendStore so that "token" (and chainId) is inside this.tx;
avoids having to pass `token` around every function, and it makes sense
to put it in the object since it is part of the tx info.

- Add account type (either node or signer) to accountsInfo

- Add account type to withAccount; output props are now `{account:
{address, type}}` instead of `{accountAddress}`