Lower blockface reservation limit to 12
Lower blockface reservation limit to 12

Fixes #950

azavea/nyc-trees,maurizi/nyc-trees,kdeloach/nyc-trees,maurizi/nyc-trees,azavea/nyc-trees,maurizi/nyc-trees,azavea/nyc-trees,RickMohr/nyc-trees,RickMohr/nyc-trees,RickMohr/nyc-trees,kdeloach/nyc-trees,kdeloach/nyc-trees,RickMohr/nyc-trees,kdeloach/nyc-trees,kdeloach/nyc-trees,maurizi/nyc-trees,azavea/nyc-trees,azavea/nyc-trees