Support scripting languages for UDFs

Patch by Robert Stupp; reviewed by Tyler Hobbs for CASSANDRA-7526
Upgrade netty to 4.0.23 enable epoll

Patch by tjake; reviewed by Jason Brown for CASSANDRA-7761
Merge branch 'cassandra-2.1' into trunk

Conflicts:
	NEWS.txt
	src/java/org/apache/cassandra/transport/Server.java
Add sanity check of $JAVA on startup
patch by Robert Stupp; reviewed by Michael Shuler for CASSANDRA-7676
merge from 2.0
Merge branch 'cassandra-2.1' into trunk
Notify DT subscribers when a column family is truncated

patch by Sam Tunnicliffe; reviewed by Aleksey Yeschenko for
CASSANDRA-8088
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	CHANGES.txt
Merge branch 'cassandra-2.1' into trunk