FEATURE: PCI-4320 - backport Juno Cinder to Folsom Nova #8

"self.configuration" does not exist in Folsom driver API.
It is a simple object, with several wrapper methods..

self.configuration.append_config_values
  will eventually call CONF.register_opts

self.configuration.<config_parameter>
  it similar to CONF.<config_parameter>

self.configuration.safe_get('<config_parameter>')
  with get the value or None. There is no equivalent in CONF.
  It is used only to get 'volume_backend_name', which is not
  even defined in Folsom. I'm making it None. Driver will
  fallback to some reasonable value anyway.
FEATURE: PCI-4320 - backport Juno Cinder to Folsom Nova #9

Revert pool-aware support from Netapp driver. AFAIK Folsom does
not support that. Folsom should be sending volume['host'] in
a form "HostA@BackendB#PoolC", but it contains only host.
Driver from the string should extract PoolC which is determines
the Netapp volume, where LUN should be created.

I have replace that code with a dummy hack to retrieve the volume
name from configuration "netapp_volume_list". This parameter
was optional and contained _list_ of volumes. I accept only
one volume now and the parameter is mandatory now.