fixing bugs #2690 and #5617 :
- preventing exception when trying to remove a node which not exist in JCR (SimpleDocumentInstanciator.java)
- adding new method to remove main app's index directory
- adding and using new method to delete all files on server when an app is definitively removed (Admin.java)
- thumbnail was not removed from file server (bad subdirectory name)
- removing some useless methods in FileRepositoryManager.java
fixing bug #5721 : adding scrollbars to window
fixing bug #5827
Merge branch 'ney-bugs-august2014' into core-5.14.x
Fixed bug #5845 (Aurore's work)
Merge branch 'bug-5845-from-work-of-aurore' into core-5.14.x
Fixing a XML/HTML content rendering of the WYSIWYG editor (Aurore's work)
Merge branch 'wysiwyg-et-code-from-work-of-aurore' into core-5.14.x