'reddit this ad' to 'discuss this ad on reddit'

Also delete a static ad file that's no longer used
Change "reddit" to "subreddit" where appropriate

This also adds new routes for /subreddits/ replacing /reddits/, though
the old routes are kept as well for backwards-compatibility
Convert or-ed startswith()s to tuples elsewhere
Replace _ in username to avoid markdown issues

When gifting a user gold, it displays their username using markdown,
so any underscores need to be replaced first to avoid having part of
a username between them interpreted as italics.

Fixes issue #714
Update and fix license headers for 2013.

Angst!
Missed some 'reddit's in compact/mobile/messaging
Use 'message the admins' in appropriate subreddit
Don't show removed comments in /comments listing
Remove reference to removed function.
Improve dev caching by naming static files based on mtime.
js: Display r.warn/error messages regardless of debug status.
spotlight: Replace stubs with internal fetch state.

Stubs are no longer necessary since replace_things is not being used by
fetch_promos any more.
spotlight: Add prefetch.
spotlight: Add fetch_promo throbber.
spotlight: Fade before first item is displayed.

This is intended to reduce the perceptual flash when promos load in.
Use consistent scaling on the timings graph

This lets one, at a glance, get a feel for how long a page took
to load. Timing data is scaled such that browser-width is 8 seconds
(unless the page took longer than 8 seconds). Clicking on the timings
will zoom the graph in for better investigation of what parts took
what amounts of time.
Remove memoize on normalize_hot.
url_escape expects unicode objects
adminbar: Allow multiple timings with the same key.
adminbar: Sort timings collection by start time.