Fixes 3PAR Host already exists error.

Fixed “Host already exists” error by,
* Screen scraping error message and extracting the host name
used by the 3PAR backend.
* Cache the host name used by the 3PAR backend for subsequent
methods using host name.
* After a restart, and 3PAR host name it no longer available,
retrieve 3PAR host name using wwn/iqn, if a terminate_connection
fails.

Fixes bug 1182134

Change-Id: Ia08a311af168ae19dbe7c1405db9c606fd878e53
Support for NFS shares with spaces in path.

Unescape share address string listed in nfs_shares_config so that
'x.y.z.w:/foo\040bar' would become 'x.y.z.w:/foo bar' to support
mounting shares with spaces in name.
Use stat command to get available and total space on device instead
of df since it's output is easier to parse.

Fixes: bug #1180984
Change-Id: I552aba91ca8db14130f854c739594a818186bbe2
Merge "Fixes 3PAR Host already exists error."
Merge "Support for NFS shares with spaces in path."