[bug 743261] Fix color of close button on modal windows

Changes the color of the close button on modal windows to white
Add Rehan to AUTHORS
[bug 757666] Add --checkindex to esstatus

--checkindex will cause esstatus to go through everything in the db
and make sure it's in the index. It's not verifying that the data in the
index matches what's in the db--only that at least something is in the
index.
[bug 757666] Add a prefix to _id

This changes _id (the document id) to include the model name. That way if
two documents have the same db id, the last-to-be-indexed document doesn't
stomp on the prior ones.

Note that _id is the elasticsearch document id and shouldn't be confused
with document['id'] which is just a field in the document named id which
matches the id in the database.

Also note that at the moment, elasticutils assumes that _id is an int, so
doing anything that causes it to do ObjectResults kicks up an error. That
needs to get fixed, but can be pushed off until I figure out how to do it
in a way that's not fundamental to how elasticutils thinks about the world.
[bug 757422] make visited links more visible
Skip the test that fails arbitrarily

This test fails like once a month. But that's annoying and it's in the queue
of things to rewrite. So for now, we'll skip it.
[bug 754079] 32x32 Favicon

Update the favicon to include the truecolor and 256-color versions of the icon at 32x32 resolution.
[bug 754042] Questions answered bar turns green at 100%

Changes the color of the questions answered bar to the standard green color when there are no unanswered questions.
[bug 757173] 3 days unanswered filter should discount Closed Threads

Make the counter and answered question bar discount closed threads,
as these should be considered answered.
[bug 755005] Promoted Helpful Answers not necessarily helpful

Make sure that answers highlighted as helpful have more helpful votes than unhelpful votes. Also ensure that the two most helpful answers are highlighted.
[bug 720935] Parallelize indexing

* reworks indexing to be parallelized when run from the admin
* changes the admin/search page to show outstanding tasks
* removes all the old progress-y stuff
* fixes the --checkindex flag for esstatus
* adds note to the ES documentation about purging celery--that's super
  helpful
Change logging name
[bug 755446] add mapping page to admin
Added survey for /kb landing page.
[bug 755594] Upgrade celery to v2.5.3 along with all it's dependencies.
Fixed celery task imports and removed unused **kwargs.
Update django-tidings.
[bug 755926] Add non-destructive indexing

* add --delete to reindex cmd: By default, it **won't** wipe the index.
  It now only wipes and rebuilds the index from scratch if you tell it to.

* add note about fixing Redis scoreboard to the docs: If you're doing dev
  work and you purge the celery tasks, you also need to reset the Redis
  scoreboard that keeps track of outstanding tasks.  This adds docs for that.

* add delete-then-index to admin: This reworks the reindex section so that
  it has a "delete-then-index" button and makes it clearer which button
  does what and why you'd use it.

* adds the DANGER style to admin page.
[bug 760706] Remove the survey on /kb landing page.

This reverts commit 920ac8ad3a3206282e0a0827f2b2447ba6039764.
Update django-tidings to fix deprecation warning.