Rename Uprev Logger class
The uprev logger object is a singleton but it is not an instance from the python logger. As a wrapper it has an instance of a python logger.
This produced a reported issue #53 (closed).
So this proposal is to rename this singleton class object and provide it to a getter to the lower level python logger object. With this, the tenacity's "after_log" will receive as a parameter the object type it expects.