SMS Game Name Changes

#### What's this PR do?
Updates vars and URLs based on naming conventions discussed in DS-206.

- SMS game endpoints are now at: `/sms-multiplayer-game/*`
- story_id is now: `sms_game_mp_story_id`
- type is now: `sms_game_mp_story_type`
- ID and type can be passed to the URL as either GET or POST params

#### What are the relevant tickets?
DS-206, DS-229