As constants not defined within a class cannot be automatically found by the
autoloader moving those constants into a class makes them accessible to
code which uses them.

Signed-off-by: Stephan Peijnik <speijnik@anexia-it.com>

Since the server doesn't support sorting, use client side sort directly
instead of calling reload() first.

Whenever a folder has a "data-share-owner" attribute, the icon is now
properly updated to a shared folder icon.

* ref comment: https://github.com/owncloud/core/issues/10392#issuecomment-52050567