create_game_json_url: Create the url with the location of NFL game JSON data
Description
This function pastes creates the JSON url for the provided game id (first
checking that it is from the 2009 season or later). The returned url is used
in the various play-by-play functions to access data from the NFL's API.
Usage
create_game_json_url(game_id)
Arguments
game_id
(character or numeric) A 10 digit game id associated with a
given NFL game.
Value
String url where the game JSON data for the given game can be found.