Fix goal specs so Timecop freezes date correctly.

I noticed that some of the goal specs were failing for me. I looked at the Travis builds, and they don't seem to be failing there, but I've been getting:

![screenshot 2014-12-09 13 07 15](https://cloud.githubusercontent.com/assets/816517/5362845/b6c5c1f8-7fa4-11e4-8cf0-4aaa3aa66b97.png)

Turns out Timecop wasn't freezing the date correctly for me. I'm not sure why I'm having the issue and Travis isn't, but it looks like it has been an issue for a lot of people at travisjeffery/timecop#100.

The fix was to convert the dates to times and pass that to Timecop.