Use relative urls everywhere

[olizilla]

Once nice feature of the deploy set up is that it publishes a snapshot of the built site to ipfs for evey commit, like: https://ipfs.io/ipfs/QmbC54Bshtcgr1ndX3zWdecbCoZdRujvuxXrkqhmcGKx5P/#/

For a site to work as expected when deployed under https://peerpad.net/ and under an ipfs path like /ipfs/QmHash, we have to use relative urls everywhere!

There are a few urls in peer-pad now that are absolute so they fail to load when viewing the site via its ipfs address:

As a side note... It'd be rad to set up a generic CI step that renders the site and checks for absolute urls