Closes-Bug: #1399014
    Adding support to display pool info for OSDs

    Fix:
        1. Added new column - Pool, to storage node disk details
        2. pool name constants DEFAULT, HDD, SSD added with their crush name mapping

    Test:
        1. checked in UI and verified new Pool column in the storage node disk grid
        2. checked for default, ssd, and hdd api cursh names

Change-Id: Ibf8f3f55726cb96ba6fecf7c60a36ebb8bfcb1ab