Build and Publishing Process

There is an history of problems with Electron Builder, the package we're now using to build and deploy IPFS Desktop's binaries to GitHub Releases and also manage our auto-update mechanism.

Currently, there are two issues opened related to our build mechanism and auto-update:

1. ~The build for macOS is failing (#1244). A quick fix for this is just using the branch from where the fix comes from (https://github.com/electron-userland/electron-builder/pull/4414) while the fix is not released.~
2. There are user concerns about the update mechanism and the entities we reach to get the new binaries (#1189, #789). A possible fix for this is to distribute the binaries using our own server.

A suggestion that would remove the need for Electron Builder and, at the same time, allowing to keep with GitHub Releases (or not), is using Electron's own packager, which requires a bit more work, but it's the official way and workable. [`electron-packager`](https://github.com/electron/electron-packager) repository.

For updates, we could use `updater.electronjs.org` with GitHub Releases to avoid the need for Electron Builder's auto-update too: https://electronjs.org/docs/tutorial/updates#updating-applications.

/cc @autonome @lidel