HBASE-7932. Introduces Favored Nodes for region files. Adds a balancer called FavoredNodeLoadBalancer that will honor favored nodes in the process of balancing but the balance operation is currently a no-op (Devaraj Das)

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.95@1481477 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/0.95' into 0.95-gd
Merge remote branch 'origin/0.95-gd' into fb-YAHOO-313-0.95-gd