Add pool support for HPE 3PAR driver

The HPE 3PAR driver does not use pools, yet. This will be enhanced to allow multiple pools per backend.

To use multiple pools per backend, manila.conf can have multiple entries of hpe3par_fpg config option, each representing a pool (FPG name).
Obsoletes: hpe3par_share_ip_address from manila.conf. Configuration now accepts IP address of share server along with hpe3par_fpg.
The format looks like:
            hpe3par_fpg = fpgname, IPaddress1, IPaddress2, IPaddress3, IPaddress4

If the share server is already setup and configured with IP address,
it need not be passed with hpe3par_fpg. It will be discovered during driver boot up.

With DHSS=True, VFS need not be configured with IP. Also the hpe3par_fpg should have just FPG name. IP address, provided by networking component (Neutron), will be assigned to VFS.