Created sal-clustering-commons and moved

sal-protobuff-encoding files to sal-clustering-commons

updated sal-distributed-datastore pom with the above change

removed sal-clustering-commons as part of distribution as it is embedded currently as part of distributed-datastore

Note - after this is merged we need to move
 out the .proto from  akka-raft to sal-clustering-commons
and add dependency of sal-akka-raft on sal-clustering-commons
and embed the same
rebased
Change-Id: I7d4ac51628cef96ffb16acfcfd596dfd3129e0fa
Signed-off-by: Basheeruddin Ahmed <syedbahm@cisco.com>