restrict max_num_tokens to 1536
patch by jbellis; reviewed by brandonwilliams and Quentin Conner for CASSANDRA-6267
merge from 1.2
Merge branch 'cassandra-2.0' into trunk
Remove CFDefinition

patch by slebresne; reviewed by iamaleksey for CASSANDRA-6253
Reject CAS queries with the native protocol v1

patch by slebresne; reviewed by iamaleksey for CASSANDRA-6270
Merge branch 'cassandra-2.0' into trunk