core: MacPoolManager-->ScopedMacPoolManager

replace use of MacPoolManager with ScopedMacPoolManager
alter commands dealing with DataCenter to include calls to
create/modify/remove pool settings related to them

if rollback occured, revert related pool setting back to former state.

Change-Id: I779f4d031409fbc422077ddf291fa34f955f3206
Bug-Url: https://bugzilla.redhat.com/1078844
Signed-off-by: Martin Mucha <mmucha@redhat.com>