Updated HpSanISCSIDriver to use initialize/terminate methods.

Updated HpSanISCSIDriver to use initialize/terminate methods.

This is based on Nirmal Ranganathan's patch for Nova-volume, which
added a new key 'host' for initialize/terminate volume connection
information in nova to fix bug 992729.

HpSanISCSIDriver should adopt the change in order to work properly.
Also added missing unit tests for the HpSanISCSIDriver.

Fixes bug 992729.

Change-Id: I9584811a340799161d8c9ae88b1def282380c9ad
Signed-off-by: Zhiteng Huang <zhiteng.huang@intel.com>