CoraidDriver: typo in _login exception handler

In cinder/volume/drivers/coraid.py, _login method, if login is
unsuccessful, we try to get the message from an undefined
object "response". Instead we should be getting it from "reply".

- errmsg = response.get('message', '')
+ errmsg = reply.get('message', '')

Fixes bug 1157499

Change-Id: Ifd047ced6b40f49881e81d4e73189d9bd216c903
CoraidDriver: do not call login from __init__

We should not call _login from the driver's __init__.
If the ESM is down, the constructor will fail.

- self._login()

Fixes bug 1157500

Change-Id: Ie57fbb6d3704d270a81cd9eb056d7988989da1f8
Merge "CoraidDriver: do not call login from __init__"
Merge "CoraidDriver: typo in _login exception handler"