The aggregation flag allowDiskUse was incorrectly named 'allowDiskUsage' which was preventing this functionality from working.
Merge pull request #1168 from joaofranca/allowDiskUse

Aggregation cursor flag 'allowDiskUse' correction
Made geoNear and geoHaystackSearch not care about what parameters are supported, #1167
Updated doc for insert function for NODE-173