Design: Handle IPFS address flavours

[olizilla]

Companion redirects all 4 flavours of IPFS address to your local IPFS repo, so you get the benefit of loading content of the distributed web. It would be rad if Desktop did something similar at the OS level.

[lidel]

I think it would be enough for Desktop to register itself as a handle that:

1. converts all types of non-HTTP addresses to a HTTP URL at our official public gateway
2. opens the URL in system's default browser

That way if user has our browser extension it will be loaded via IPFS anyway, but everyone else will still be able to load via public gate.

[hacdias]

I think that would be a great idea @lidel.

This one is related to ipfs/ipfs-desktop#35.