REST API and Cluster Management.
New Features
* REST API Server - Issues [82](https://github.com/HDI-Project/ATM/issues/82) and
[132](https://github.com/HDI-Project/ATM/issues/132) by RogerTangos, pvk-developer and csala
* Add Cluster Management commands to start and stop the server and multiple workers
as background processes - [Issue 130](https://github.com/HDI-Project/ATM/issues/130) by
pvk-developer and csala
* Add TravisCI and migrate docs to GitHub Pages - [Issue 129](https://github.com/HDI-Project/ATM/issues/129)
by pvk-developer