Fixes a bug where failing at publishing a note would redirect to Admin::ContentController#edit and crash the application instead of redirecting to Admin::NotesController#edit as it should. Issue #247.

Makes Admin::NotesController inherits from Admin::BaseController like Admin::ContentController and Admin::PageController.

Moves private method parse_date_time from Admin::ContentController to Admin::BaseController to avoid code duplication.
Merge branch 'bugfix_7.x'