add schema tracker support
add native protocol v3 support
Merge branch '151-2.1' into 361

Conflicts:
	driver-core/src/main/java/com/datastax/driver/core/Cluster.java
	driver-core/src/main/java/com/datastax/driver/core/KeyspaceMetadata.java
	driver-core/src/main/java/com/datastax/driver/core/Metadata.java
	driver-core/src/main/java/com/datastax/driver/core/ProtocolEvent.java
	driver-core/src/test/java/com/datastax/driver/core/CCMBridge.java