Fix inserting empty maps

patch by slebresne; reviewed by jbellis for CASSANDRA-5141
Merge branch 'cassandra-1.2' into trunk
fix get_count returns incorrect value with TTL; patch by yukim reviewed by slebresne for CASSANDRA-5099
Merge branch 'cassandra-1.1' into cassandra-1.2

Conflicts:
	src/java/org/apache/cassandra/thrift/CassandraServer.java
Merge branch 'cassandra-1.2' into trunk