SAN/Solaris driver fixes

Fixed error handling for the Solaris SAN volume driver. Missing (unknown) LUID no longer causes an error - None is returned from now on.

This allows other functions to raise an error or treat this as a normal situation (for example, on volume deletion, if no export had ever taken place).
Also repaired SSH execution argument passing for the SAN base - double string join was used, resulting in c h o p p e d  c o m m a n d s.