Add function to drop individual table.  Refactor droptables to keep single codebase.
Add function to drop individual table.  Refactor droptables to keep single codebase.

losinggeneration/gorp,xiaoenai/gorp,coopernurse/gorp,outdoorsy/gorp,kevinc0825/gorm,mousesun/gorp,gabelula/gorp,coopernurse/gorp,evenco/gorp,kevinc0825/gorm,losinggeneration/gorp,rickb777/gorp-old2,rickb777/gorp-old2,GeertJohan/gorp,cortex/gorp,kimxilxyong/gorp,go-gorp/gorp,cortex/gorp,d-g-laptev/gorp,evenco/gorp,gabelula/gorp,d-g-laptev/gorp,outdoorsy/gorp,kimxilxyong/gorp,GeertJohan/gorp,go-gorp/gorp,yp-engineering/gorp,xiaoenai/gorp,yp-engineering/gorp,mousesun/gorp