Fails in strict mode

[axelson]

Since _getDataToSend is defined as an implicit global variable (along with a few other functions), this library will fail to load when run in Javascript strict mode (i.e. "use strict";) with the error: ReferenceError: _getDataToSend is not defined.

I believe that angular-payments should be changed to define those functions as local variables so that it doesn't cause issues in strict mode and leak variables into the global scope. Looking at the functions they don't appear to be meant to be loaded into the global scope.