MB-100: revised mixed test

Change-Id: I731ca4ec218f198d9cd5d06c701c0f086eaf1a76
Reviewed-on: http://review.couchbase.org/27410
Reviewed-by: Ronnie Sun <ronnie@couchbase.com>
Tested-by: Ronnie Sun <ronnie@couchbase.com>
MB-100: added new mixed/read tests

Change-Id: Iee568a327d4311b60e238b99aa57a159305050d6
Reviewed-on: http://review.couchbase.org/27411
Reviewed-by: Ronnie Sun <ronnie@couchbase.com>
Tested-by: Ronnie Sun <ronnie@couchbase.com>