[#4019] ticket:480 Simple UI for ticket filtering

No real data yet, just placeholders
[#4019] ticket:481 choices_for_filters
[#4019] ticket:481 Prevent unnecessary calls to solr for filter choices
[#4019] ticket:481 JS for filters
[#4019] ticket:481 Filter search
[#4019] ticket:481 Switch mongo/solr query based on filter
[#4019] ticket:481 Add facets to MockHits. Fixes a lot of test failures.
[#4019] ticket:481 Use one query for facets and search, when possible

When using solr search, we could get facets and search result in one
query.

- It saves one query to solr on every request to pages with ticket list
- It returns choice options based on search result, thus options that
will produce empty result are not displayed to user, and counts are
right.

When mongo search is used (filter is not active) - fetch facets in
separate solr query.
[#4019] ticket:481 Fix milestone filter
[#4019] ticket:481 Make filter and displayed columns work together
[#4019] ticket:481 Apply filter to bulk move and bulk edit
[#4019] ticket:481 Fix test
[#4019] ticket:481 Add some unit tests
[#4019] ticket:515 added escape for search query
[#4019] ticket:515 Revert wrong test edit and make another test more clear
[#4019] ticket:515 Don't escape the `q` query

Because it contains query provided by used which already in solr syntax
and could be escaped already.
[#4019] ticket:513 Fix choices for filter by status on milestone view
[#4019] ticket:514 added dropdown UI
[#4019] ticket:514 fix UI and test
[#4019] ticket:514 clean templates and js