Maestro 0.1.7

* Deep expend of environment variable list values.
* Pre-processing of the YAML environment description file with Jinja2
* Pass in specified volumes to create_container() in case the image's
  Dockerfile didn't define them.
* Support service-level environment definitions that apply to all
  instances.
* Fix port bindings passed to start(), more precise description of
  internal/external ports and how they are placed in the environment.
* Improved and extended documentation.
* Use docker-py 0.3.x.
* More unit tests and progress towards Python3 compatibility.

Signed-off-by: Maxime Petazzoni <max@signalfuse.com>