Co-locate meta and master

With this patch, HMaster is also a HRegionServer. Active master can serve some small tables per configuration (by default, it doesn't). Backup masters don't serve any region. HMaster and HRegionServer share the same RPC server. That's transparent to clients since the master information is in ZK. The master and the regionserver also shares the same web UI server. There is no protocol, or API change. So this feature is backward compatible, and rolling upgradable. In case it's needed, some configurations ( HBASE-10815 ) will be added so that (1) we can have two web UI servers in the master (and backup masters), one for the master, and the other for the region server; (2) we can leave backup masters alone and don't put any regions on them. So that things are the same as before. With this patch, the following configurations are removed (and not used any more): hbase.master.dns.interface hbase.master.dns.nameserver hbase.master.port hbase.master.ipc.address hbase.master.zksession.recover.timeout fail.fast.expired.active.master hbase.master.handler.count