HBASE-12510 Make hbase-consensus independent of HRegionInfo (and other cruft removal)

Summary:
We need to remove HRegionInfo from hbase-consensus (and in general all HBase dependencies, but they aren't blocking us right now). This is because:
(1) We cannot use our internal HRegionInfo while trying to have a quorum on the WAL.
(2) The open source HRegionInfo is different from ours (No QuorumInfo, no HTableDescriptor etc.)
(3) We will depend on hbase-client, while hbase-client depends on us (hbase-consensus). This is a cyclic dependency, and will fail to compile.
(4) Using HRegionInfo in hbase-consensus doesn't make sense regardless of (1 - 3) because the quorum should be independent of the underlying KV store.

Apart from this, I moved the RMap related parts to hbase-server. Need to finish a couple of TODOs there. Also, started using ServerName instead of HServerAddress, wherever possible.

Test Plan: Unit tests

Reviewers: shroffrishit, aaiyer, fantasist, adela

Subscribers: eclark, zelaine.fong

Differential Revision: https://reviews.facebook.net/D29685