Support same index name in different keyspace in Cassandra-1.2

We encounter exception when using same index name in different keyspaces.
This feature won't exist until Cassandra 3.0, but we're using 1.2.

Cassandra:3.0
https://github.com/bitus-dt/cassandra/blob/cassandra-3.0/src/java/org/apache/cassandra/config/CFMetaData.java#L877
https://github.com/bitus-dt/cassandra/blob/cassandra-3.0/src/java/org/apache/cassandra/schema/KeyspaceMetadata.java#L110


Cassandra-1.2
https://github.com/bitus-dt/cassandra/blob/cassandra-1.2/src/java/org/apache/cassandra/config/CFMetaData.java#L1054

In order to use same index name in different keyspaces without upgrade Cassandra.
We fork and patch this feature to our branch.

Branch: https://github.com/bitus-dt/cassandra/tree/cassandra-1.2
Commit: https://github.com/bitus-dt/cassandra/commit/85487ad55c253ac43d4980cf30b9cfeac256af0f