Added filesystem hooks for mount/unmount ext storage
Added failing unit tests for mount config hooks
Expose getAppKeys trough \OCP\IConfig
Fix add/remove mountpoint hooks
Add EtagPropagator to handle etag changes when external storages are changed
Hookup the etag propagator
More phpdoc
Added PHP docs for etag propagator
Merge pull request #11305 from owncloud/ext-updateetagonmount

Update etag of parent dir when adding/removing ext storage mount points