This commits includes:
1. Restructuring of the directories so that command line entry points
are in `dcos.cli`
2. Refactored out the generic config functionality to a reusable
module
3. Basic implementation of the marathon cli for starting an
application
4. constant module for storing generic constants needed by multiple
modules
5. Rudimentary marathon interface using the HTTP REST api
6. Added dependency on python's requests module/library
8349692faf