Try out Electron 2.0

[etpinard]

I don't see anything breaking changes from the list on https://electronjs.org/releases#2.0.0, so the upgrade should be fairly simple.

We might want to explore new possible solutions for #12 and try out --headless as mentioned in #22.

Some thorough testing of our image server will be required though.

[etpinard]

... to do after the v1 release.

[etpinard]

... and electron 3.0 and 4.0

• https://electronjs.org/blog/electron-3-0
• https://electronjs.org/blog/electron-4-0