Get gitlab to build and host sourcecode documentation (built on #89)

• Add another gitlab case which actually runs the tests as well

• Remove compile only job

• Create a non-root user and try to run as them

• Change the new user name

• Add a few useful debugging statements

• Actually check status of tests

• Initial attempt at building a gitlab pages site automatically

• Make sure docs build has python available

• Try to install pip

• Correct doc target name

• Only build docs on changes to master and next

Auto-generated documentation hosted at https://gyrokinetics.gitlab.io/gs2/

This PR includes the related gitlab changes in #89