limit the usage of connection_info
limit the usage of connection_info

Related to blueprint xenapi-volume-drivers

The connection_info parameter, that is coming from volume contains only
two keys, 'driver_volume_type', and 'data'.
See:
https://github.com/openstack/nova/blob/master/nova/volume/manager.py#L375

parse_volume_info was checking the connection_info for 'auth_method',
and authentication parameters. These informations live inside
connection_data. This patch is fixing this, and covering with a test.

Also rename the generic data variable to connection_data, to make it
easier to read the code.

parse_volume_info thus no longer depends on the whole connection_info,
only on the connection_data.

Also clean-up some copy-paste test setup code.

Change-Id: I5289120d46176c8528c3317a650269c4f384f930

n0ano/gantt,n0ano/gantt