Make JS,CSS,IMAGES conditionally defined.

This allows app's to redefine these constants as necessary.
This makes these constants consistent with their *_URL relatives.
Fixes #GH-1170
Remove pointless code.

Add a missing call to parent::setUp() and remove code that it takes
care of.
Fixing comment for  in TimeHelper __construct
Merge pull request #1215 from andreaskri/timelinehelper_comment_fix

Fixing comment for  in TimeHelper __construct
Fix array('disabled') and array('disabled' => true) working differently.

The shortform should work the same as the longer form with regards to
disabling field locking with SecurityComponent.

Fixes #3734
Merge branch 'master' into 2.4