Fix prepared statement on thrift post-6659
Fix Cassandra 2.0.x validates Thrift columns incorrectly

patch by thobbs and slebresne; reviewed by thobbs and slebresne for CASSANDRA-6892
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	src/java/org/apache/cassandra/config/CFMetaData.java
	src/java/org/apache/cassandra/config/Schema.java
	src/java/org/apache/cassandra/cql/QueryProcessor.java
	src/java/org/apache/cassandra/cql/SelectStatement.java
	src/java/org/apache/cassandra/cql/UpdateStatement.java
	src/java/org/apache/cassandra/db/Column.java
	src/java/org/apache/cassandra/thrift/ThriftValidation.java
	src/java/org/apache/cassandra/tools/SSTableExport.java
	src/java/org/apache/cassandra/tools/SSTableImport.java
	test/unit/org/apache/cassandra/SchemaLoader.java
	test/unit/org/apache/cassandra/db/ScrubTest.java
	test/unit/org/apache/cassandra/thrift/ThriftValidationTest.java
	test/unit/org/apache/cassandra/tools/SSTableExportTest.java
Fix error with super columns in mixed 1.2-2.0 cluster

patch by slebresne; reviewed by iamaleksey for CASSANDRA-6966
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	src/java/org/apache/cassandra/db/SuperColumns.java