Fix broken build
Improve error message when trying >= 2.0 on java < 1.7

Patch by brandonwilliams reviewed by thobbs for CASSANDRA-7137
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	conf/cassandra-env.sh
Remove unused isLocalTask method.

Patch by Lyuben Todorov, reviewed by brandonwilliams for CASSANDRA-7181
Merge branch 'cassandra-2.0' into cassandra-2.1