Convert User Panel and User Nav Panel to BS3.
Convert Accounts' templates to BS3.

Includes login, signup, password reset, profile and profile update.
Add ACCOUNTS_APPROVAL_REQUIRED to TEMPLATE_ACCESSIBLE_SETTINGS.

This is used for displaying a help message in accounts/account_signup.html
Add some margin on top of messages.
Use small buttons in ratings.
Highlight active items in tree navigation.
Style non-field errors in forms.
Style error messages as danger alerts.

Django messages are tagged with "error", while BS3 error class is
called "danger". Let's just duplicate BS3 styles to target "error".
Get rid of alerts in accounts, search results, comments, and blog filtering.

Also, add glyphicons to deleted/unmoderated comments.
Make .timespan styles available everywhere, not only as child of .twitter.
Set input max-width to 300px and textarea to 400px.

We define max-width instead of width to avoid messing up inline forms
(like the search form on top).
Target HTML5 form fields too.
Limit width for .datefield and .datetimefield.