Added option to limit the number of activity feeds

Hey Casey,

I'd like to use this widget for my website, so thanks for making it!  Right now I'm limiting the number of activity feed items by using css, but I figured I'd throw you a pull request to see if you'd like to make it a feature.  I checked the API to see if limiting was an option on the recent events request, but couldn't see anything.  Let me know what you think.

Tom