Changed default error_val parameter to None in get_percent_crowd_agreement().  Previous devault of -1 was causing query problems.  Nonetype converts to NULL in OGR output.
Changed default error_val parameter to None in get_percent_crowd_agreement().  Previous devault of -1 was causing query problems.  Nonetype converts to NULL in OGR output.

SkyTruth/CrowdProjects