Removed duplicate usage of TempestConfig()

Change-Id: Iac50547d3f48ec12d2b7e82454581ca5d8fbcbc2
Adding new test for iSCSI live block migration

Requrires a new config value as the test depends on a
specific patch being made to XAPI to support the
relax-xsm-sr-check behaviour

Change-Id: I217f0e377fe08fb5d0ae9213d8b04f6c319f7ecc
Cleaned up volume

Change-Id: I2f501a10c5bd2093c7f73d0bd8b6491b2c99ea2a