I am trying to calculate the number of full financial quarters between two dates using momentJS. Unfortunately I don't think that moment has quarter difference handling. Did I miss it or should I make a feature request?

For example, with the following code I'd expect the result to be 1 because the entire first quarter of 2014 (Jan 1 - Mar 31) is contained within those dates.

```
var beginDate = moment('2013 12 31');
var endDate = moment('2014 04 01');

endDate.diff(beginDate, 'quarters')
// should return 1

```

With this code I'd expect the result to be 2 because the the first and second quarters of 2014 are contained.

```
var beginDate = moment('2013 12 31');
var endDate = moment('2014 07 01');

endDate.diff(beginDate, 'quarters')
// should return 2

```

I tried this but it produces unexpected and often incorrect results.

```
Math.floor(endDate.diff(beginDate, 'months') / 4)

```

Any input you have is appreciated. Thanks.