Link shares always allowed deletion, however internally the permissions
were stored as 7 which lacked delete permissions. This created an
inconsistency in the Webdav permissions.
This fix makes sure we include delete permissions in the share
permissions, which now become 15.
In case a client is still passing 7 for legacy reasons, it gets
converted automatically to 15.
A share can only be requested by 3 'types' of people
* owner
* initiator
* recipient
So we have to get the path as the current user. Since that is the only
path that has any meaning to the user.