Got the OData search working.

I've added a "Maximum result size" value to the base datasource class,
which defaults to 1000.  This should be implemented by all data source
classes, although the OData one is presently the only one that actually
does.  I need to add it to the ArcGIS one as well.

Now that the results are normal sized, it basically just works.  The
search completes, Datajs handles the deserialization, and it gets passed
off to slickgrid for display.