Path to README.md can be passed in as argument

* refine tests
* introduce `readme_path` to the config
* fix the case of codeblock variations which doens't format correct in the
  frontend
Merge pull request #160 from tonini/clear-tests

Path to README.md can be passed in as argument
exit script properly
Merge pull request #162 from tonini/prevent-exit-info-issue

exit script properly