Add workloads that test truncation of capped collections.
Make changes based on CR comments.
Have maxdocs capped collection workload extend the size-based one.
Need to call db.collection.find() before calling itcount().
Change distinct() back to find().
Add workload for in-memory mapReduce command.

Still want to refactor so that it can be used as the base for other
map-reduce workloads
Restructure map_reduce_inline.js workload.

Now is compatible with incremental map-reduce operations using the
"merge" output action.
Some minor formatting changes.
Change to use bulk API for inserts.
Add map-reduce workloads that write to collections.
Fix up some comments.