This reverts commit 8e4c509d.

This reverts commit 4c984df1.

* master:
  promise/plugin: improve check-rx-saturated messages

See merge request !119

See https://pypi.org/help/#description-content-type

In some deployments it is important to being able to select only specific
senses on which the promise shall react.

See also nexedi/slapos@4230cd1b

Tests are rewritten for easier coverage of all cases, including all-ok case.
In the same time code has been improved while detecting inconsistencies.