Add Event on DbProvider.

Add Predicates/Exists class.
Add Predicate HasTag
Merge pull request #218 from inthause/documents

Add Event on DbProvider, Add Predicates/Exists class.
[FIX] fix numeric document property modification
[NEW] Add Job namespace
Merge pull request #219 from inthause/documents

[NEW] Add Job namespace
[FIX] fix website resolution
Merge pull request #220 from inthause/documents

[FIX] fix website resolution
Added rbs_tag_search table.
HTML is now allowed in main menu entries.
Changed pre-defined page sizes in pagination.
Cleanup.
- Event names are now constants in "RbsChange.Events".
- Enhanced Tags management and reduced dependencies between Rbs_Tag and core.
Removed dependency with rbschange.js.
Renamed <todo/> to <rbs-todo/>
Renamed <todo/> to <rbs-todo/>
Enhanced Rbs_Media menu with the use of Rbs_Tag.
Renamed "query" attribute to "filter-query" on <rbs-document-list/>. A "load-query" attribute is about to arrive, to define a query object to be used for the initial load.
Added "load-query" attribute to define a query object used for the initial load.
Renamed "query" attribute to "filter-query" on <rbs-document-list/>.