Add "fig push" command

This command pushes any docker images that are declared as builds in the fig.yml to a docker repository. You can figure the repository using --repository-name or -r at the command line. This is a good starting point for figuring out how to deploy a fig stack into a production/cluster environment without having to make any assumptions about what this environment looks like.
There is a bunch of name parsing code that expects fig images to always be in the form <project>_<service>_<index>, does this pass the integration tests?  Does it cleanup all the images afterward?