BibMatch: 'fuzzy' result mode addition

* Adds a new result mode called 'fuzzy' that can be used in
  validation rule-sets to allow one rule to fail validation and
  marked instead as a "fuzzy" match.

* Amends the regression test to check local restricted collection
  matching ONLY if the CFG_SITE_SECURE_URL is set to HTTPS protocol.
  (Otherwise the InvenioConnector returns an error.)

* Adds tests and amends documentation for the added feature.

* NOTE Amends the default Invenio config to put an example fuzzy rule.

Signed-off-by: Jan Aage Lavik <jan.age.lavik@cern.ch>