HBASE-12197 Move rest to it's on module

Summary:
Move hbase-rest to it's own module.
copy test resources from hbase-server into hbase-rest's test resources.

Test Plan: Unit tests pass of hbase-rest module.

Differential Revision: https://reviews.facebook.net/D24657
HBASE-12210 Avoid KeyValue in Prefix Tree (Ram)
HBASE-11394 Replication can have data loss if peer id contains hyphen "-"
HBASE-12126 Region server coprocessor endpoint (Virag Kothari)