Feature request: support for deploying directly from a git remote

_From @olalonde on March 24, 2016 20:25_

It would be nice if the controller supported deploying apps by specifying a git remote URL. e.g. `deis pull https://github.com/deis/example-nodejs-express.git` or `deis deploy https://github.com/deis/example-nodejs-express.git`. That would make it easier to eventually have a "Deploy to Deis" button like [Heroku](https://devcenter.heroku.com/articles/heroku-button).

_Copied from original issue: deis/deis#4994_