Disable tests that you don't need

[zegl]

No Kubernetes cluster is similar to the next one, and kube-score should be adaptable so that everyone can use it. While still keeping sane defaults.

I'll add a flag --disable-test that can be specified multiple times to disable all of the tests that you need. Another flag --list-tests will print a list of all tests, to make it easy to know which tests that you might want to disable.

Issue #46 and #48 are both related to this.