#9 ferment_time function should adjust for started batches

[Kevin Nowaczyk]

I've updated the ferment_time function to be simpler (in my mind at least), and more accurate.

However, if a batch has already started, the dates returned from this function should shift accordingly.

For example; if the beer is racked a week late, the recommeneded bottling date should move by a week. To accomplish this, the function must pull those dates, parse out the day, month and year for each step that exists, and set $aprimary, $asecomdary, $pmonth, $smonth, etc.

Kevin