workflows tasks: code quality and workflows tasks bug fixes

* Fixes PEP8 & sphinx mistakes.

* Adds more documentation to some functions.

* Removes useless and obsolete code, factorize some parts.

* Changes the start workflow function to give the
  possibility to start from a new clean BibWorkflowObject.

* Adds the refresh frequency as a parameter for workflows
  synchronisation.

Signed-off-by: Guillaume Lastecoueres <guillaume.lastecoueres@cern.ch>
workflows: cleaning and sphinx fixes

* Fixes sphinx mistakes.

* Removes useless regex.

Signed-off-by: Guillaume Lastecoueres <guillaume.lastecoueres@cern.ch>
workflows unit tests: respect new code modification

* Updates workflow to comply with the modification in
  tasks librairies.

* Fixes an error with the new ObjectVersion type with
  python3.

Signed-off-by: Guillaume Lastecoueres <guillaume.lastecoueres@cern.ch>