also fix the returned keys

syntax is the same has http://www.php.net/manual/en/function.hash-file.php

Refactoring OC_APPCONFIG and OC_PREFERENCES, minor changes to OC_APP. These libraries are skeletons only, the functions need to be written.

Conflicts:
	admin/templates/index.php
	templates/layout.admin.php
	templates/layout.user.php

All conflicts are fixed.

  * Full PHP tags
  * Alternative syntax for control structures
  * Semi-colon at the end of instructions

* We have to use full tags (<?php) and not short tags (<?)
* We have to use the alternative syntax for control structures (see http://www.php.net/manual/en/control-structures.alternative-syntax.php).

This could be useful if the user does not want his gallery images on the webdav storage.

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

fixes http://bugs.kde.org/show_bug.cgi?id=264295

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

in the (rare) case that there are unreadable files show an error since it's probably a case of incorrect premissions set by someone.