Fulltext search refinements

* enable empty query `q=&...` to return all visible objects (or counts
  therof)
* include `NULL` in list of visible contexts
* enable `counts_only=true` query parameter to return the count of
  matches per type
* deduplicate `results.entries`
Refined show/hide of "Map to this object" link in sidenav extended info
Story 52269321: Mapping from lefthand nav objects to page object
Basic mapping support for more object types.  Directive-to-Control throws not implemented error.
Track changes to multiple objects
Add behave tests for event and revision logging
Merge pull request #82 from reciprocity/feature/sidebar_object_mapping

Mapping of lefthand nav objects to page object
Merge branch 'release/0.9a6'
Merge tag '0.9a6' into develop

Sprint 6
Merge pull request #84 from reciprocity/feature/objectnav-refining

Feature/objectnav refining
Merge pull request #83 from reciprocity/feature/log_events

Behave tests and support for multiple object logging
Merge pull request #79 from reciprocity/feature/search-refinements

Fulltext search refinements
Proper program contexts are created, now. Further, basic roles needed to
allow users to be assigned roles in program contexts are automatically
created. Behave tests to validate the new capability are included.

Also, a minor improvement was made to the alembic wrapper ggrc.migrate
to enable the revision command to create a new version for an extension
module.

Finally, a dependency has been added to requirements.txt for the blink
package to enable signals. We'll use signals as an extension mechanism,
with signals providing an explicit hook for contribution to processing,
such as when a new resource is posted.
Merge pull request #86 from reciprocity/feature/objectnav-refining

Added affix to lhs nav, fixed overlapping with object nav
Merge pull request #85 from reciprocity/feature/basic_roles_seeding

All changes required to enable assigning users a role in a private program.
Merge pull request #87 from reciprocity/feature/objectnav-refining

Feature/objectnav refining
Unify and semi-fix width sizing on load and on resize
Add 'edit object' link to info.mustache

* also added 'data-widget-view' on Program info widget to handle
  specifying a different 'widget_view' mustache template for InfoWidget
  controller