Allow custom configuration loader

patch by slebresne; reviewed by jasobrown for CASSANDRA-5045
Add binary protocol to stress

patch by slebresne; reviewed by yukim for CASSANDRA-4993
Merge branch 'cassandra-1.2' into trunk

Conflicts:
	tools/stress/src/org/apache/cassandra/stress/Session.java
Fix typo in patch for #5081
Merge branch 'cassandra-1.2' into trunk