should add "PATH: process.env.PATH" while spawn a subprocess

That is, [Line 78 of Wallet.js](https://github.com/elevenbuckets/11BE_SimpleWallet/blob/master/Wallet.js#L78) should change to something like:
`env: {DISPLAY: process.env.DISPLAY, XAUTHORITY: process.env.XAUTHORITY, PATH: process.env.PATH, configDir},`

In some cases there's no `node` in the default PATH, for example, people who use `nvm`. In such case, `launchGUI()` would fail due to cannot find `node` and return error message "path not found".

Start at line 78 of Wallet.js, where launchGUI() spawns the subprocess. Reproduce the failure in an environment using nvm or otherwise lacking node in the default PATH. Done means launchGUI() can find node and no longer returns the “path not found” error.

Written by the indexing model from the issue text.