Properly handle parsing huge map and set literals

patch by Aleksey Yeschenko; reviewed by Sylvain Lebresne for
CASSANDRA-5893
Merge branch 'cassandra-1.2' into cassandra-2.0.0
Fix CHANGES.txt
Merge branch 'cassandra-2.0.0' into cassandra-2.0
Add ability for CQL3 to list partition keys

patch by Aleksey Yeschenko and Dan Jatnieks;
reviewed by Sylvain Lebresne for CASSANDRA-4536