sqlalchemy: fix default integer constructor

* Addresses issue with default constructor on types that do not
  accept arguments in SQLAlchemy>=0.7. (closes #1776)

Signed-off-by: Leonardo Rossi <leonardo.r@cern.ch>
workflows: object navigation

* Adds buttons for going to previous/next object from the main table
  in the Holding Pen detailed display. The previous/next functionality
  is based from the state of the main table order.

Co-authored-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
Signed-off-by: Georgios Papoutsakis <georgios.papoutsakis@cern.ch>
workflows: update of MARC views

* Updates the HTML, RAW and MARC views in the details page.

Signed-off-by: Georgios Papoutsakis <georgios.papoutsakis@cern.ch>
workflows: PEP8 fixes

Signed-off-by: Georgios Papoutsakis <georgios.papoutsakis@cern.ch>
workflows: signals addition

* Adds signals to workflows for when a workflow is started, halted
  and finished.

Reviewed-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
Signed-off-by: Georgios Papoutsakis <georgios.papoutsakis@cern.ch>
workflows: formatted data from model

* Moves the logic of properly formatting and escaping the data
  from the BibWorkflowObject in Holding Pen from the blueprint
  to the model.

Reported-by: Jiri Kuncar <jiri.kuncar@cern.ch>
Signed-off-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
oaiharvester/workflows: small task update

* Updates tasks to fix some issues when harvesting with oaiharvester.

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