matcher: Legacy code deletion

* Legacy BibMatch module removed as it's no longer used.

Reported-by: Jiri Kuncar <jiri.kuncar@cern.ch>
Co-authored-by: Jan Åge Lavik <jan.age.lavik@cern.ch>
Signed-off-by: Graham R. Armstrong <graham.richard.armstrong@cern.ch>
matcher: API documenation formating for Sphinx

* Reformatted the docstring comments for creating API documentation
  with Sphinx, added API to api.rst

* Minor formatting fixes; including requested changes for merging
  into PU.

Signed-off-by: Graham R. Armstrong <graham.richard.armstrong@cern.ch>
matcher: Unit tests fixes, new helpers.py

* Unit tests fixed to prevent flask context errors, now using local
  and lazy imports; all Matcher tests passing.

* New helpers.py file added, provides common or separate functions
  for use in unit tests.

* Bugfix for CeleryFeeder skipping last result.

Signed-off-by: Graham R. Armstrong <graham.richard.armstrong@cern.ch>