Removed the daily search index task

I think this is causing site issues.  I'm going to replace it with a
hopefully better way.
Added management command to index all videos for a team.

I know we are going to need this for the TED speaker name change, so I
snuck it in here.
Added DebuggingTimer class

This isn't used anywhere, and it probably won't be in production code.
It's nice to use when we're debugging performance issues though.
Added management command to profile indexing 1 video

Refactored the video search index a bit so that things that
potentially could take a long time are in their own method.  This
makes profiling easier.
Seedup indexing videos / generally speed up subtitle data operations

The way we handled videos/languages/versions was pretty inefficient
for typical use cases.  For example in the search we want to index the
video title for all languages.  This means we would:

  - Fetch the video from the DB
  - Fetch all the languages from the DB
  - For each language, we would do a query to get the tip (this would
    be many queries if the video had a lot of languages)
  - For each tip, we would call get_title(), which might default to
    the video title, in which case we would do another query per
    language tip to re-fetch the video
  - We would call video.get_title(), which would check the title for
    the primary audio language, so that would re-fetch the language
    again and re-fetch the videos again.
  - If we wanted to now fetch the subtitles for a language, we would
    call get_tip() again, which would re-fetch the tip

Added a bunch of speedups here:
  - Cache the tip version for SubtitleLanguage.get_tip()
  - Cache languages in Video.subtitle_language()
  - Added Video.all_subtitle_languages() which caches the results
  - Add a SubtitleLanguage queryset method that fetches the languages
    and then joins all the tips to those languages using a single
    extra query.
  - Set the _video_cache attribute when we create SubtitleLanguage and
    SubtitleVersion objects.

All of these changes makes indexing happen in about 12% of the time on
my system.
Added command to continuously index the site

Added copywrite notices on top of other search commands
Fixed using the --rate argument
Merge pull request #844 from pculture/better-indexing

Better indexing