Extract update_repo method
Rename build_api_url to build_api_compare_url

We want to add a call to another API endpoint, so make the existing
method name a bit more specific.
Move api_compare_url and http_compare_url to object
Split repo update into an update and redraw method

As well as cleaning up the split between code which is working things
out based on the API response and code which is rendering stuff to the
view, this lays the groundwork for calling redraw independently of
updating the repo from an API call to the compare endpoint.
Merge pull request #5 from evilstreak/split-update-and-render

Split update and render
Move CSS out of index and into it's own file
Switch from vw to em for font sizing

This was causing problems on screens, and for variable numbers of repos (eg, 4 was ideal, more caused problems)
Refresh the whole page once every 3 hours

As this usually runs on radiator screens it's easier if updates happen automatically,
without having to go find a keyboard and mouse. This will refresh the same URL and
load any changes.

Frequent enough to get changes, not so frequent it visibly refreshes to often