Delete BS2 static resources. Add BS3 resources: css, js and fonts.
Migrated base.html and all it's includes to BS3.
Forms: Migrated mezzanine.forms to BS3 and added custom styles.
Forms: Fix jQuery snippet to correctly focus the first form input.
Convert pagination template to BS3.

- pagination class is applied to ul, not wrapper div
- Page info element should be a span, not an anchor, since is not
meant to be clicked.
Convert right panel to BS3 in base.html.

Also remove excesive top margin in the first header of a panel.
Convert mezzanine.blog to BS3.

Includes blog post list, detail, filter panel and custom styles.
Remove excessive whitespace from mezzanine.css.
Convert ratings to BS3.
Display messages in the alternative blog post list views as info alerts.
Convert search results to BS3.
Convert error pages to BS3.

- Don't leave the meta title empty.
- Present the error in a panel.
Convert gallery to BS3 and use Magnific Popup with it.
Don't assume all ratings go inside a panel.
Convert comments to BS3.

Major refactor of the comments template, reduces duplicate markup
and uses more of Bootstrap's goodies (alerts, icons, etc).
Synch transifex translations for cset a9946f4b68dc
Style password inputs.

Thanks to @mjtorn!
Strip query parameters from url in thumbnail tag

In the thumbnail mezzanine template tag, check if there are query
parameters in the image url and strip them.
Convert Twitter app to BS3.

- Retweets now use Glyphicons.
- Added a permalink to each tweet.
- Each element has classes for easy targeting and styling.
Convert User Panel and User Nav Panel to BS3.