SDK proposal.

- to create, delete, list secondary index.
- to query secondary index.

Change-Id: I4886625f4f8b6f316c415bf095102c8e684afc28
Reviewed-on: http://review.couchbase.org/43774
Reviewed-by: Pratap Chakravarthy <prataprc@couchbase.com>
Tested-by: Pratap Chakravarthy <prataprc@couchbase.com>