Add gitbase-spark-connector to the compose file

[carlosms]

After the latest roadmap discussions about EE and CE, sourced-ce will deploy only one docker-compose.yml, there will not be 2 versions.

CE will be similar to what we have today, but using gitbase-spark-connector.
Since there is still some work needed in other projects, we will start working with PRs against a new branch, gsc.

Until we have a proper public release of gitbase-spark-connector, we will have to use the private -enterprise image.

Open question: what will we do with the sourced sql command.

[se7entyse7en]

Open question: what will we do with the sourced sql command.

Related to this: #170.

[se7entyse7en]

See here.