Don't run a query to fetch all languages for tasks

The query was pretty slow (> .5 seconds) and it was fetching languages
for all tasks, including completed tasks, so it wasn't very useful.
Instead, just let users choose from any language.
Shortcut counting tasks when there's a ton.

Right now TED has over 10,000 open tasks.  Counting them is actually
fairly slow.  This changes things so that if there are more than 1000
tasks, we just display "> 1000"
Speedup for task.get_perform_url()

The old code made a several DB queries just to get the URL to perform
a task.  This changes things so that we just return a URL immediately,
then do the queries if the user clicks on one of the URLs.
Merge remote-tracking branch 'origin/staging' into speedup-tasks

Conflicts:
	templates/teams/_context_project.html
Merge pull request #803 from pculture/speedup-tasks

Speedup tasks