WebSearch: initial support for recjson output

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>
BibCheck: properly reset last_run timestamp

* When using the -a/--all CLI parameter of BibCheck,
  actually performs to reset of the last_run timestamp
  only upon execution of the bibtask and not when it is
  scheduled.

* Improves bibtask verbosity.

Signed-off-by: Samuele Kaplun <samuele.kaplun@cern.ch>
BibCheck: new creation_date check

* Exploits the BibCheck infrastructure to backdate the
  creation date of a record based on the actual content of
  its metadata. In this way tools such as BibSort will be
  able to properly sort records according to their real
  creation.
  (closes #1719)
  (closes #1604)

Signed-off-by: Samuele Kaplun <samuele.kaplun@cern.ch>
BibSort: creation date and ingestion order

* Introduces proper sorting by creation date, exploiting
  new bibcheck plugin introduced in previous commit and
  consequently backward compatible "ingestion order"
  sorting.

Signed-off-by: Samuele Kaplun <samuele.kaplun@cern.ch>