remove opencv submodule from repository

As noted in #5, the OpenCV libraries can be installed directly via
apt-get.
Dockerfile: install OpenCV into the container

OpenCV is packaged for Ubuntu. Add an appropriate ``apt-get install``
line into Dockerfile to install the libraries and the Python bindings.
Merge branch 'master' into remove-opencv

Conflicts:
	src/Dockerfile
Merge pull request #6 from rjw57/remove-opencv

remove OpenCV from the repo