This makes it possible to maintain backwards compatibility with configs
created when manual actions were non-blocking.
From now manual actions are blocking if configured with `allow_failure:
false`, otherwise manual actions are optional, and their status is
ignored.
Instead of using:
`coverage: /\(\d+.\d+%\) covered/`
This structure must be used now:
```
coverage:
output_filter: /\(\d+.\d+%\) covered/`
```
The surrounding '/' is optional.
This commit:
* Turns `coverage_regex` into `coverage` entry in yml file
* Fixes smaller requests from code reviewers for the previous commit
* This commit is temporary (will be squashed afterwards)
This commit does not (further commits will do though):
* Add global `coverage` entry handling in yml file as suggested by Grzegorz
* Add specs
* Create changelog
* Create docs
