Documentation additions

- Provide note about timeout settings accuracies
- Include recently added operations for lcb_cntl
- Add documentation about error classifiers

Change-Id: Iac820318749f88968ac657a68186793d00863018
Reviewed-on: http://review.couchbase.org/35002
Reviewed-by: Brett Lawson <brett19@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Remove unused variables from get replica

We don't use the VBC stuff there anyways

Change-Id: Id07267013a87e09884c94677e5279cf593720450
Reviewed-on: http://review.couchbase.org/35032
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Brett Lawson <brett19@gmail.com>