Remove coordinator batchlog from materialized views

We are considering removing or making optional the coordinator batchlog.

The batchlog primary serves as a way to quickly reach consistency between base and view since we don't have any kind of read repair between base and view. But we do have repair so as long as you don't lose nodes while writing at CL.ONE you will be eventually consistent.

I've committed to the 3.0 branch a way to disable the coordinator with -Dcassandra.mv_disable_coordinator_batchlog=true

The majority of the performance hit to throughput is currently the batchlog as shown by this chart.

http://cstar.datastax.com/graph?stats=f794245a-4d9d-11e5-9def-42010af0688f&metric=op_rate&operation=1_user&smoothing=1&show_aggregates=true&xmin=0&xmax=498.52&ymin=0&ymax=50142.4

I'd like to have tests run with and without this flag to validate how quickly we achieve quorum consistency without repair writing with CL.ONE. Once we can see there is little/no impact we can permanently remove the coordinator batchlog.