Add latency aware load balancing policy

JAVA-129 #fixes
Fix changelog
Fix potential overflow in RoundRobinPolicy

Also correctly catch exceptions if balancing policy throws.

JAVA-184 #fixes
Merge remote-tracking branch 'datastax/1.0' into 2.0

Conflicts:
	driver-core/CHANGELOG.rst
	driver-core/src/main/java/com/datastax/driver/core/Cluster.java
	driver-core/src/main/java/com/datastax/driver/core/Connection.java
	driver-core/src/main/java/com/datastax/driver/core/Metadata.java
	driver-core/src/main/java/com/datastax/driver/core/RequestHandler.java
	driver-core/src/main/java/com/datastax/driver/core/ResultSetFuture.java
	pom.xml