Added trotIn and trotOut animations

Hi,

This is my first crack at contributing on Github. Apologies in advance if I break the Internets.

Please find the Pens that illustrate the new animations:

trotIn: http://codepen.io/anon/pen/luiKe
trotOut: http://codepen.io/chrishardie/pen/LzaeC

I believe these should be placed in the "Special" category, though I'm unclear how exactly I should be categorizing them per the README

The min file was generated by the YUI compressor, wasn't sure if you had a preferred tool for this.

If I haven't completely borked on this attempt, I'll add more :)