Fixes 3PAR Host already exists error.

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