also fix the returned keys

Start of the refactoring. Commit is quite big because I forgot to use git right from the beginning. Sorry.

 - return the app in privateDataGet
 - implement privateDataDelete
 - split key-value storage from ocs parsing/output so plugins can use it for storage to

handle the app paramater with private data get correctly according to the spec

still fails under sqlite (and probably postgresql) but I will look more into that later

PHP function names is case-insensitive so this change isn't
intrusive but improve readability of the code.

add Open Collaboration API support. You can now connect your ownCloud with the KDE Social Desktop and push notifications to your Social News Plasmoid. This requires KDE trunk or KDE SV 4.5