Ensure eager-loading of `Event.revision`

* Also, don't eager-load `modified_by`, since it will be mostly
  repetitive; instead use `#using` in the mustache template
Add `<controller>._ifNotRemoved` wrapper in TreeView

* `_ifNotRemoved` checks for existence of `this.element`, and should be
  used for any callbacks where the controller may be removed from DOM
  before the callback completes
Check for dirty session before starting request

* This should prevent database connections from being shared between
  requests, even in the event of timeout / error race conditions.
Add the correct binding in `MappingResult.get_bindings()`
Fix use of `DirectListLoader` when resources are linked

* Also stop using `table_plural` in favor of explicit links
Improve eager loading on `Person` objects

* The heavy loads will also use `.user_roles`, so include it inline
* Also remove previous `undefer` workaround since SQLAlchemy 0.9 fixed
  the problem.  (Original problem was causing `undefer` of *all*
  `people` loads, including linked objects.)
Add support for `__page_only` query parameter

* `__page_only` returns paging information without returning any actual
  data
Change Program page `People` widget to use TreeView

* Removes old `authorizations_list_loader`
* Adds `with_program_roles_as` Mustache helper
* Adds `TreeView` templates in `ggrc_basic_permissions` module
* Adds `Program.mapped_and_or_authorized_people` mapping
Clean up usage of `ListView` controller

* Remove all non-mapping `list_loader` implementations except
  `model_list_loader` for Admin page
* Fix Admin initialization by using new `__page_only` query parameter to
  get counts without loading resources
* Use query parameters instead of multiple searches with a client-side
  merge
* Make usage of `paging` data uniform (not requiring `find_function`,
  but still using `list_view_options.find_params`)
* Reduce default paging size to 50 (from 100)
* Add attribute specification for `Event.modified_by`
Merge remote-tracking branch 'origin/develop' into feature/improve-people-search

Conflicts:
	src/ggrc/assets/javascripts/controllers/tree_view_controller.js
Merge remote-tracking branch 'origin/develop' into feature/improve-people-search
Add indexes on People and Events

* People.name, People.email
* Event.updated_at
Merge pull request #1302 from reciprocity/feature/improve-people-search

Improve people search