Added almond option for almond.js builds

I noticed an [issue](https://github.com/gruntjs/grunt-contrib-requirejs/issues/29) asking for automated almond.js builds which the grunt-requirejs plugin provides, and I have added an `almond` option which allows you to easily configure it. This is a performance gain for apps that are optimizing to a single file as the almond library is really small and is bundled with your build file rather than having to do a http request for require.js then your app.js file.

I see this as a valuable option for this task, as without some mechanism to do this, you would have to maintain a separate html file with the almond script tag instead of the require.js script tag.