Final cleanup of gitlab-ci.yml for optimal testing

- testing support for 2.7 and 3.6
2 jobs for 40-python3port in 2 minutes and 8 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test Python 2.7
passed #1294
Go-py2.7

00:00:56

 
  Test Python 3.6
passed #1295
Go-py3.6

00:01:11

15.0%