use the correct command to get annex status
use cached repository git status/git annex status in view
use jQuery to update collection git status after initial page load

Getting git status for every repo in the collections list page
takes a long time once collections get big.  Statuses are now
retrieved by jQuery after the page has finished loading.

Room for improvement: If we had a function that returned status
only on cache hits, we could load status into the view context
and only use jQuery for cache misses.