Simple CSS hacks to make Moodle look like Bootstrap.

So I'm using this branch to put all my "conservative" LESS/CSS hacks into. They should make certain parts of Moodle look more Bootstrappy, and clean up the CSS but I've avoided including some of the more extreme things I've used in the past. They 'worked' to some degree but were too hacky and fragile to put into something that other people would actually see. But it does mean that often the Moodle Base look shines through. 

Most of these have been used and tested at our institution for a while. Though I've slightly edited and reshuffled them so there's probably bugs. 

I'm not doing anything renderer related in this pull request, though I might do a seperate one, again with the most conservative and least controversial renderers only.

Feel free to ignore this or cherry pick anything you find useful.