Move helper function up a level for easier extensibility

So, this function is causing weeks to start on Monday (day # 1), despite the fact that both `moment().startOf('week')` and `moment().localeData()._week.dow` are returning `Sun Nov 09 2014 00:00:00 GMT-0500 (EST)` and `0` respectively.  At minimum, I'd like to fix this via a decorator, however, I'm curious if this behavior was your intention.