devilry_examiner: Hello world skelton for dashboard.
devilry_examiner: Removed old app.
devilry_examiner: Started on a GruntJS+bower+bootstrap setup.
devilry_examiner: Working bootstrap+GruntJS setup.
apps.core.models.assignment: Created a manager for examiner queries.
devilry_examiner.views.dashboard: Very simple plain ul listing.
apps.core.models.assignment: Added a DefaultAssignmentManager.

Required because ``objects`` disappeared when we added
``examiner_objects``.
devilry_developer.testhelpers.soupselect: Added.
devilry_examiner.views.dashboard: Tests.
apps.core.tests.assignment.TestExaminerAssignmentManager: Tests for ExaminerAssignmentManager.
src/devilry_extjsextras/devilry_extjsextras/static/devilry_extjsextras/form/DateTimeField.js
src/devilry_subjectadmin/devilry_subjectadmin/static/devilry_subjectadmin/app/controller/CreateNewPeriod.js

* Catching change event and update the end_time datepicker to block
  out dates earlier than start_time.
* #487