change default request timeout from two minutes to four minutes

#### What's this PR do?
This extends the timeout of our `request.post()` calls to mobilecommons from 2 minutes to 4 minutes. We've created a modified request object within `mobilecommons.js` with its default timeout extended. 

#### Where should the reviewer start?

#### How should this be manually tested?
By playing through a variety of game functions, the `mobilecommons.profile_update()` and `mobilecommons.optin()` functions were tested--they still work to opt in users and update their profiles. The actual timeout limit hasn't been tested. 

#### Any background context you want to provide?
Our requests to "https://secure.mcommons.com/profiles/join" subscribes users to opt in paths, unsubscribes them, and updates their profiles. Some of our calls to this API were throwing 408 timeout errors. 

It could be that MobileCommons' servers are taking a while to return a response. By extending the timeout of our Post request, we hope to mitigate these errors. 

#### What are the relevant tickets?
Closes #256.