Fix tests that carry meta in Master that were disabled by Proc-V2 AM in HBASE-14614

The following tests were disabled as part of Core Proc-V2 AM in HBASE-14614

• TestRegionRebalancing is disabled because doesn't consider the fact that Master carries system tables only (fix of average in RegionStates brought out the issue).
• Disabled testMetaAddressChange in TestMetaWithReplicas because presumes can move meta... you can't
• TestAsyncTableGetMultiThreaded wants to move hbase:meta...Balancer does NPEs. AMv2 won't let you move hbase:meta off Master.
• TestMasterFailover needs to be rewritten for AMv2. It uses tricks not ordained when up on AMv2. The test is also hobbled by fact that we religiously enforce that only master can carry meta, something we are lose about in old AM

This JIRA is tracking the work to enable/modify them.