Added bootstrap to base; upgraded it to 2.3.2; alerts now prettier and deletable
Removing global bootstrap; just using alerts code now.
Moved alerts code into it's own stylesheet to keep things cleaner
Reverting bootstrap to 2.3.1
Fixed on central server; cleaned up messages section of base for both dist and central
Merge branch 'release-0.11' of github.com:learningequality/ka-lite into pretty_alerts

Conflicts:
	kalite/templates/base.html
Wrapping alert dismissal in an unload function
Added back in element where AJAX messages get inserted.
Turns out the javascript is completely unnecessary.
Merge pull request #966 from dylanjbarth/pretty_alerts

Pretty alerts