CCBC-190: Config cache issues during conf changes

This fixes several issues relating to configuration changes while using
a cached configuration.

This also handles CCBC-195, CCBC-196, CCBC-197, and partially handles
CCBC-198.

Change-Id: Iadd9099087f119ac659326c88edbad9456fc753a
Reviewed-on: http://review.couchbase.org/25420
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>