remove unnecessary assertions regarding number of PUT checkpoint requests.

https://github.com/couchbase/couchbase-lite-android/issues/398
testAllLeafRevisionsArePushed passing

https://github.com/couchbase/couchbase-lite-android/issues/398
testRemoteConflictResolution() passes

https://github.com/couchbase/couchbase-lite-android/issues/398