Improve -t and -y flags

[JohannesWiesner]

Currently, when setting the -t flag, the script will always use test.yml as input but it should be possible to hav all these options:

1.) Test mode with environment.yml
2.) Test mode with custom .yml file provided with -y
3.) No test mode with environment.yml
4.) No test mode custom .yml file provided with -y

I think this could be solved with nested getopts.

• When -t is provided without -y, always fall back to test.yml
• When -y is provided without -t, always fall back to no running testing mode