Boot from volume Server side infrastructure

  * Block Device Mapping introduced in Request model object
  * Boot from volume enabled for server client
  * Added Unit test case for the model changes
  * Fixed issues after Daryl review
  * Added xml tests
  * Removed split

Change-Id: I9817f4899fcd5b718b54f9a427e9232e6c6a6113
Merge "Boot from volume Server side infrastructure"