Added atami.com.sv to sites in README.
Fix add_to_builtins import for Django 1.7
Initial version of new admin menu
Fixing messages location
Messages tweak
fix broken links
Added Federico Bruni to AUTHORS
Merge
Adds docs for HOST_THEMES configuration.
Made a few grammatical fixes.
Removed a caveat that can go in the PR comments.
Update css to make side nav full height.  Add js to open/close section subnav.

--HG--
branch : admin_nav
Merge
Don't animate the admin menu when first loading
Better defaults for non-english language codes.
Added setting ADMIN_MENU_COLLAPSED for controlling admin side-nav behaviour.
Remove dashboard link from admin menu - replace with cliackable Mezzanine title.
Highlight selected item in admin nav.
Move site/lang drop-downs into top nav bar.
Bigger buttons throughout admin