Fix sharing of ext storage mount points

When sharing an ext storage mount point, it will now use the name of the
mount point instead of an empty string for the target path.
Added unit test for sharing ext storage mount points
Fix getPathById for Oracle

Added extra code to handle the case of Oracle which saves empty strings
as null values.
Memcached hasKey should test for success, the get can fail for other reasons.

One of the other failures is no running server.
Merge pull request #8499 from owncloud/shareextstoragemountpointfix

Fix sharing of ext storage mount points
[tx-robot] updated from transifex
Merge pull request #8512 from owncloud/fix-memcached-hasKey

Be more strict in checking the resultCode of memcached hasKey function

* owncloud/fix-memcached-hasKey:
  Memcached hasKey should test for success, the get can fail for other reasons.