SNOPTWrapper: Name snopt minimum workspace constants
SNOPTWrapper: Name snopt minimum workspace constants

SNOPT documents that the 8-char, int, and real workspaces must each have
at least 500 elements.  Encapsulate these values in named constants.

psiorx/drake,psiorx/drake,sheim/drake,billhoffman/drake,billhoffman/drake,sheim/drake,sheim/drake,psiorx/drake,psiorx/drake,billhoffman/drake,billhoffman/drake,psiorx/drake,psiorx/drake,psiorx/drake,psiorx/drake,sheim/drake,sheim/drake,sheim/drake,billhoffman/drake,billhoffman/drake,billhoffman/drake,sheim/drake,billhoffman/drake,sheim/drake