Refactor sanitycheck

While deprecated, this still takes up a lot of place in our code. Make
it a bit slimmer :)

Change-Id: Ic0d078aeb3a41629edf06eb835a995d4b35024cc
Reviewed-on: http://review.couchbase.org/39928
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Brett Lawson <brett19@gmail.com>