Refs #76: update max supported gcs protocol version when get quorum. fix to compute right action size of state request when STR
Refs #76: use act_proto_ver to control format of STR
Refs #76: renaming. when we refers to group_protocol_version
1. core->proto_ver and core->group->quorum.gcs_proto_ver mean highest common supported version
2. core->group->gcs_proto_ver means its own max supported version. although name is bit confusing.
Refs #76: use repl_proto_ver instead of gcs_proto_ver to control STR message format
Refs #76: allow gcs protocol version to downgrade
Refs #76: since we bump repl_proto_ver, we dont need to bump gcs_proto_ver.
Refs #76: galera replicator supports str_version 2
Refs #76: renaming
Refs #76: use STR version to control using donor selection or not
Merge galera-3.x upto 3a949e6edec46862b8cd91b2a0ad7536ee5d0438