some weird mobile browser behaviours

now allows to cycle through multiple images

warning mentions preview into area where actual content would be

Make the streaming API also handle websockets (because trying to get the browser EventSource interface to
work flawlessly was a nightmare). WARNING: This commit makes the web UI connect to the streaming API instead
of ActionCable like before. This means that if you are upgrading, you should set that up beforehand.

fix bug in process feed service

Adds support for, among other things, 

Fix #205, fix #156, fix #124

status clickable (this also fixes multiple dropdown being openable at the same
time)

entire timelines (only fetch since last known ID). Side effect: account
timelines no longer update in real-time