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)
Fix query and aggregation of role implications

* Collate roles and contexts to issue a single query for all
  RoleImplication objects
* Fix aggregation of roles and contexts to handle the case where a user
  has one role in multiple contexts
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
added BETA to people in LHN
improvements for audit popover to show all necessary info
added asterix for mandatory field
Merge pull request #547 from reciprocity/feature/audit-modal-fields

added asterix for mandatory field
Merge pull request #546 from reciprocity/feature/audit-popover-improvements

improvements for audit popover to show all necessary info
Merge pull request #545 from reciprocity/feature/beta-adding-lhn

added BETA to people in LHN
Icons for top-level tree icons are now hidden (it's implied by the section's header icon)
Made the scrollable area larger for expanded search results
Merge pull request #548 from reciprocity/feature/widget_list_icons

Icons for object in widget top level trees no longer display icons
Merge pull request #544 from reciprocity/feature/fix-https-issues

Fix HTTPS issues
Use case-insensitive regex flag to avoid rejecting capitals.
Merge pull request #537 from reciprocity/feature/emailValidFix

Lowercase given email before checking against regex.