Added filtering for PBC requests
Sticky header partial updates:
handling more than one header at a level
expandable/collapsible headers as for PBC request filters

This is a WIP.  Sending to Andy for further review
tree filter controller (missing from previous commits)
Fixed issues with sticky headers where headers outside the viewport were used in header positioning computations (also reverted some prior changes as they resulted in regressions)
Fixed an issue where headers with a height taller than the "scrollaway margin" were disappearing early
Fixed error on blanking date field
WIP - attempting to make clone filters look like originals in all cases
Merge branch 'develop' into feature/pbc-filters

Conflicts:
	src/ggrc/assets/mustache/audits/tree.mustache
Fixed a merge typo
Updated sticky headers to use the original header elements as the sticky ones (using the clones as placeholders)
adding Status in all modal objects
standard headline icon fix
Merge pull request #632 from reciprocity/feature/standard-icon-fix

standard headline icon fix
Only show 'System' and 'Admin' roles on Admin Dashboard

* Previously, all of "Private Program", "Auditor" and "* Implied" roles
  were also shown and editable/deletable.
Merge pull request #634 from reciprocity/hotfix/fix-admin-page-roles-query

Only show 'System' and 'Admin' roles on Admin Dashboard
Bump to Version S16.1
More fixes for Admin Roles widget

* Show "Private Program" roles also
* Ensure both "System" and "Admin" roles are non-editable
Merge pull request #635 from reciprocity/hotfix/fix-admin-page-roles-query

Version bump; more Admin Roles fixes
Fix options on Product and Control modals
Fix `defer_render` and use for `select` elements

* Hopefully the final form of `defer_render`
* Change implementation of `option_select` and `category_select` to fit
  new/old-but-fixed behavior