Fix tap GitHub repo list

[dherbst]

This is for #48, it goes through the project list and then looks at each one to find the code_url, and only adds the ones that are on github to the meltano.yml file.

You can run the tap and see the data in stdout by doing this:

First, copy .env to cfp-data-pipeline/meltano/cfp-pipeline

docker-compose run --entrypoint=bash --rm meltano
$ meltano install tap-github
$ meltano invoke tap-github