Merge pull request moment#40 from luisfarzati/gh-pages

Interval plugin

source/docs/plugins/interval.md

@@ -0,0 +1,22 @@
+Interval is a plugin that lets you create time intervals easily.
+
+```javascript
+// using two moment objects
+var june2013 = moment.interval(moment('2013-06-01'), moment('2013-06-30'));
+
+// using ISO 8601 expressions
+var lastWeek = moment.interval('P1W/');
+
+// relative to a moment instance
+var tenHoursQuarantineStartingNow = moment().interval(moment.duration(10, 'hours'));
+```
+
+Full documentation and sources [here](http://github.com/luisfarzati/moment-interval).
+
+It's available on npm like so:
+
+```
+npm install moment-interval
+```
+
+Or just grab the JS file from [here](https://raw.github.com/luisfarzati/moment-interval/master/src/moment-interval.js).