This ended up spread over multiple commits. Trying to break into phases for review:

Add server version detection, normalize schema event processing, refactor schema parsing:
https://github.com/datastax/python-driver/compare/9f69d53af28cc81ed8511c2d1691eb6cc110126d...483d7d366d44380c748aec01abe688e07a911f3e

Metadata file updates from that point:
https://github.com/datastax/python-driver/compare/179d0b6503028e54af6b4b5da509cce2e04fe21a...2803bb734dbd941fb0bb125003d53ab20fbdb0c3#diff-a29357fb1c1566fef0634fe1caa2c964

Mike has reviewed some of this over the course of C* betas and rc1.

Pushed two more minor commits - for beta2 to https://github.com/iamaleksey/cassandra/commits/6717-3.0

Both are relatively minor and with descriptions in the commit messages.

@Sam Tunnicliffe python driver is updated on 276 branch here (3e8621). Please let me know when this should proceed to the cassandra-test branch for cassci.

(see also: a comment about a possible anomaly observed while testing)

The next step in CASSANDRA-6717 is to move secondary index metadata out of column definitions and into a separate table. I've pushed a preliminary branch with a new system_schema.indexes table here.
Things to note, further changes are imminent (i.e. before 3.0 beta 1), which will include support for multiple indexes on a column, multiple target columns for a given index and real per-row indexes, which don't target any specific columns. The new indexes table is designed for those new features, but they're not actually implemented in that branch.

Note for next iteration: Instead of literally modeling schema columns and only hiding columns on CQL generation, we need to model the logical table. See https://issues.apache.org/jira/browse/CASSANDRA-9813
and
https://datastax-oss.atlassian.net/browse/JAVA-873