Merge pull request #3 from ChiSamurai/master

bugfixes
Fixes on handling permissions
- Collections should now use rwx------, ACEs only r-- or rw- without
executable bit.
- provide "isExecutable" for collections submitted (checkuser.xql)
- display Dynatree-toolbar-buttons according to correct permissions
(query.js)
- adding an ACE only gives mode "r--" instead of "r-x" (sharing.xqm)
bugfix 
- display pref image and avoid non-imageIs-relations