Update EASE version (includes base reqs)

@singingwolfboy This pulls in the change [you reviewed earlier today](https://github.com/edx/ease/commit/a990b25ed4238acb1b15ee6f027465db3a10960e).

@jzoldak @benpatterson This implicitly adds a new requirement which could slow down the Jenkins builds (fisher==0.1.4).  Anecdotally, the installation is pretty quick, but it may be worth adding to the AMI eventually.