Fix Storwize terminate_connection with no host

Nova may pass a connector to Cinder with no 'host' field, which was
causing a KeyError in the Storwize driver. This patch resolves this case
by doing the following:
1. If the volume is mapped to only 1 host, unmap it
2. If the volume was not mapped or mapped to multiple hosts, print a
   warning but don't raise an exception

Change-Id: I0ec1c24adbdfbcf1c4868b4981a2e2618d4b411c
Closes-Bug: #1244257
Fix suppressed exceptions for migration downgrade

In SQLAlchemy migration versions 009, 010 and 020, we missed
reraising exceptions while logging errors in case of a downgrade.
We don't want exceptions to pass silently. This patch fixes that.

Closes-bug: 1227881

Change-Id: Id11b1c5d2e26d208e88bb84e5b46c4b7affc3f9f
Updates .gitignore

To ignore swap files from getting into repository
currently the implemented ignore is *.swp
however vim adds more swap files if .swp exists,
so improving this with .*.sw?

Closes-Bug: #1255857

Change-Id: I22b6fa351dd565d4783f432c01785c706acd8397
Merge "Fix suppressed exceptions for migration downgrade"
Merge "Fix Storwize terminate_connection with no host"
Merge "Updates .gitignore"