Add ssl option

Hi,

My Pivotal Tracker projects have the use SSL option enabled so I cannot use whereuat without this patch.

I couldn't find any tests to add to so I didn't add any :(

I tried to test using `rake dev` but I kept getting a boot error because it couldn't load dev.rb. Instead, I just added my local gem path to the app I was trying to use whereuat with and verified that it worked.

Before this feature, while using my app I was getting a 400 error on the request when you click the whereuat tab. Now, it loads up my stories as expected when I set pivotal_tracker_use_ssl to true.

Let me know if you need any other changes made, but this works great!

Thanks,

Jake