Improved logging by adding more user information and more illustrative stack traces

#### What's this PR do?
Adds more informative information to our MobileCommons API error logging. Not only do we add phone numbers and form data (containing opt in paths) to our error logs, we also include a stack trace. 

Note that we placed the trace generation outside of the callback. Otherwise, all the information our trace would give us would be within the callback. 

#### How should this be manually tested?
I manually tested the `optin()` and `profile_update()` functions of this PR by 1) running the functions normally, throwing no errors, and then 2) selectively modifying the functions to throw either a) errors returned by an invalid request made, or b) errors messages returned by the MobileCommons API. All tests were made with Postman. 

To generate the first kind of error, I modified the mobilecommons url so that our request wouldn't hit a valid endpoint. To generate the second kind of error, I modified the arguments provided to mobilecommons, so that there would not be valid optin or user information. 

#### What are the relevant tickets?
Closes #255