Bump to Latest Version of Electron 2.0.X

[say25]

Please describe the problem you think should be solved
It looks like Electron 3.0 is stable and 4.0 is getting closer and closer to arriving, so making the jump up to the latest stable release of Electron 2 will help with testing once we decide to dip our toes into the next major versions of Node and Chromium. (This is mostly copy pasta from #5613).

This also allows me to avoid using a shim for missing TypeScript definitions addressed in Electron 2.0.13 as noticed over in #6051.