1) increase max sockets to 100, 2) revert create solo game changes, 3) small fixes

#### What's this PR do?
1. Increases http max sockets to 100, as per #339. 
2. Re-adds a `response.sendStatus()` call deep within a `createUser()` function callback in order to ensure asynchronous solo game creation processes happen in order, as per #375. 
3. Small fixes, like that within the .`findUserGame()` function. (The `phone` variable was undefined within that function.) 

#### How should this be manually tested?
`npm test`ed, as well as postman creating solo and multiplayer games. 
Great, thanks!