Cells: Update set_admin_password for objects

Cells code was calling the compute/api set_admin_password method with an
old-world style instance and failing on the task_state attribute access.
This adds set_admin_password to the list of methods handled via the
cells RPC redirect method which is objects compatible.

Change-Id: I12e212260ed62dc9380202de31fda928a9498dcb
Closes-Bug: #1335315
Don't swallow exceptions in deallocate_port_for_instance

This uses the new _delete_ports method to (1) still
ignore 404 errors but also (2) raise up non-404 errors
from the neutron client when deleting the port fails as
we shouldn't be masking over this since the nova-api
call wouldn't be failing even though the underlying
operation failed.

Change-Id: Id05ea47ba03e0b60ae3a296920159e8189f9dd55
Related-Bug: #1292243
Improve secgroup create error message

Fixes secgroup create API so that when it is passed a name
or description field which is an empty string the error message
specifies which field is of the incorrect format.

Change-Id: Ieff67438965a735f2328390125bb4e66aec5e83d
Closes-Bug: 1369358
Merge "Improve secgroup create error message"
Merge "Don't swallow exceptions in deallocate_port_for_instance"
Merge "Cells: Update set_admin_password for objects"