Toil to Mesos

[stevencox]

Connect Toil to our Ansible deployed Mesos cluster.

Probably configure the Toil scheduler implementation to point to our newly created Mesos instance.

This will likely involve installing Toil on all worker nodes, and that's probably Python 2.7 dependent.

[stevencox]

On further review of Toil, a more practical approach for the MVP is to implement the Toil batch scheduler interface to communicate with Chronos. That will have all three of our CWL execution engines working with Chronos.

[stevencox]

Implement the abstract batch scheduler interface in Toil to send tasks to Chronos.