Add :save option to FileDepot.depot_hash=.

So that a file depot can be validated without saving the record into DB.

https://bugzilla.redhat.com/show_bug.cgi?id=1151173
Add FileDepotFtp.verify_depot_hash

to validate the ftp credentials.

https://bugzilla.redhat.com/show_bug.cgi?id=1151173
Cleanup LogFile.verify_log_depot_settings.

connect_ftp method has been removed when some of the logic was moved into FileDepot and its subclasses.

https://bugzilla.redhat.com/show_bug.cgi?id=1151173
Let FileDepot.verify_depot_hash support ftp validation as well.

It currently supports NFS and Samba validation thru LogFile.verify_log_depot_settings.

https://bugzilla.redhat.com/show_bug.cgi?id=1151173
Use FileDepot.verify_depot_hash to validate ftp along with NFS and Samba connections.

https://bugzilla.redhat.com/show_bug.cgi?id=1151173
Add test cases.

https://bugzilla.redhat.com/show_bug.cgi?id=1151173
Fix spec for MiqSchedule where FileDepot's uri is set to nil.

https://bugzilla.redhat.com/show_bug.cgi?id=1151173