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. 
And we should just remove this commented out line so we don't confuse ourselves later about whether or not it should be there.