added base level of security (filetype check) to uploadhandler
added base level of security (filetype check) to uploadhandler

ARISGames/server,tl-its-umich-edu/ARISGames-server,tl-its-umich-edu/ARISGames-server,ARISGames/server,tl-its-umich-edu/ARISGames-server,ARISGames/server,ARISGames/server,tl-its-umich-edu/ARISGames-server