Partial-Bug: #1378454
 -Feature: Send IPMI information of the cluster from server-manager
           to Cassandra database
 -Fix: Created ipmi.sandesh file to hold the structure to be sent.
       Modified viz.sandesh and vns.sandesh to have the sandesh structure
       elements.
  Made changes for review-1
  Made changes for review-2
Change-Id: I62b15ff36e535ad70cc209f43aae6200243a4b1e