Here is the initial work for converting hubs to using the fedora boostrap. It would be nice to get this in as a start, so we can all build on it as we add new stuff. merging templates is not much fun (i found out) because I had some issues merging this in because of the addition of the add widget functionality, but i think i got it merged ok, and working as before.

a few notes on this:

• i am currently holding a built version of fedora-bootstrap in the static dir here on hubs, because there were some changes i made to fedora-bootstrap that i needed, but when this is released, and hosted like the other fedorabootstrap css/js, we can change that URL.
• fedora bootstrap uses bootstrap4, and the glyphicons are no longer bunded with bootstrap, so i included the openiconic set, like in pagure.
• added a quick icon for the header, this is more a placeholder, it needs approval and work.
• currently pulling in the fonts from google fonts, this needs to change in the future.

one major change here that needed some work was that panels dont exist in BS4 anymore, they are replaced by cards. I also started removing some of the custom styles in the CSS that were replaced by styles in fedora-bootstrap.

oh, and here is a screenshot:

Ok so this PR breaks a lot of things (moving widgets around in edit mode, the layout of the feed widget) but this will happen anyway with such changes, so I'm going to merge it as for this kind of breakage, the earlier the better