Added functionality, Grunt, tests

Not sure if you care to update ics.js or if it was something you built for a purpose and it has long since accomplished it. Thank you for creating it as I needed it for a project of mine. 

In that process I changed it a bit. I'm sending this PR in case you want the changes. If not, no worries.

I added Grunt and Bower for the dependency management, minification, and testing. I added some simple tests and changed the object a bit so a user could add more than one event if desired.