NetApp: Clean up lock file left behind by unit tests

The synchronization decorator added to the NetAppISCSIDriver class
creates a lock file named cinder/openstack/cinder-netapp_dfm
during the unit tests. This commit cleans it up.

Fixes bug 1135619

Change-Id: Iec41a0f23d4a1c6668bdcb451c2c02efd3f97500
Improved fail_reason for cinder-backup swift connection errors

Modified swift backup service to catch socket errors when talking to
swift and raise a specific SwiftConnectionFailed exception in these
cases. This allows us to provide a more readable error message
detailing the problem connecting to swift to the end user when they
view the backup. Also reduced the default number of swift retries
so devstack environments fail faster - production environments can
tune these in cinder.conf.

Fixes bug: 1132791

Change-Id: Ibca744ea5adcbd31d068ac3d858bde6a4a0c9844
Merge "Improved fail_reason for cinder-backup swift connection errors"