Remove unused dependencies

[Varunram]

We should combine this with other PRs, if possible

Unused dependencies
* bignumber.js
* crypto
* debug
* eth-lightwallet-nwjs
* hooked-web3-provider
* koa
* koa-route
* koa-session
* koa-websocket
* mkdirp
* node-localstorage
* os
* path
* promise-queue
* reverse-line-reader
* serve-favicon
* tmp
Missing dependencies
* nw.gui
* y18n

y18n might not to be needed, nw.gui might have to check

[cryptofuture]

https://github.com/Musicoin/desktop/pull/185/commits/8c9258c8b03824387deb1351216697510916f5d1

[Varunram]

Closed via https://github.com/Musicoin/desktop/commit/8c9258c8b03824387deb1351216697510916f5d1