Volume types need to be specified when creating CG

When creating a consistency group, the scheduler will find a backend that
supports all input volume types. If volume types are not provided, the
default_volume_type in cinder.conf will be used, however, this could cause
inconsistent behavior in a user environment where the default_volume_type
is defined in some places but not in others. This fix removed the use of
default_volume_type for CG creation, added a check to verify that volume
types are provided when creating a CG.

When creating a volume and adding it to a CG, we need to make sure a
volume type is provided as well.

Change-Id: I078d4fdd8d92529e853be16272ad74d1e130f712
Closes-Bug: #1366371
Merge "Volume types need to be specified when creating CG"