Add admin interface for links and users.
Output profile edit form using <p> tags and remove colon from labels.
Hook up milestone list and stats block on profile page.
Update to latest django-csp and add wp.com to allowed image domains.

This should fix an issue with gravatars not showing on the dev server.
Disable X-Frame-Options when DEV = True and flesh out middleware list.
Spacing.
Use BaseModelAdmin in links admin.
Return 'Unknown' size when image file is missing.
Move leaderboard to helper and hook it up on the homepage.
Hook up global stats on homepage and make Get Started login button work.
Replace leaderboard view with generic view and rename migrations.

Also removes some unnecessary docstrings.
Move upgrade banners out of media directory and ignore it again.
Various template updates/fixes

* Added home page header graphi
* Added thanks message in newsletter signup
* Added smart banner info popup
* Added placeholder message for no banners
* Some other general tweak-and-tidy
Only show no links message if you have no links.
Remove placeholder from newsletter form.
Bug 976774: Add message for number of clicks/downloads since last visit.

Includes an upgrade to a non-released version of factory_boy because it
has an amazing decorator that disables signals for factories. It's not
used in production, so who cares?!
Show previews of banners in generator and links on dashboard.
Hook up smart banners properly.
Add preview to customization page of both versions of upgrade banners.
Hook up newsletter signup.