Do deployments for Beanstalk

Adds a tool to do deployments for an app hosted in github.

The tool inspects the git repo in the directory it's used from to determine the name of the application and to build the package.

Details on installation and usage are in the [README](https://github.com/alphagov/digitalmarketplace-deployment/blob/rob-play/README.rst)

I'm having trouble with this step...
`Command /usr/bin/git clone -q https:/github.com/alphagov/digitalmarketplace-deployment /var/folders/n7/_mnvw1g55nlgr811vfh216pw0001jk/T/pip-jtZBQA-build failed with error code 128 in None`