workflows: actions JS loading

* Makes the JavaScript assets loading for actions separated from
  the general assets loading to allow for easier additions of
  actions on overlays.

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

* Enriches the documentation of the Workflows module by adding
  more information on actions and the Holding Pen.

Signed-off-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
sorter: multiple tag sorting fixes

* Fixes issue in sorting according to multiple MARC tags.

* Fixes issue with ordering of sorted records as well as handling of
  unsorted records.

* Fixes record slicing issue using 1-indexed value instead of
  0-indexed value.

* Adds generic method to decide whether to rank or sort records and
  changes facets to use this method.

* Adds two configuration variables to control default sort field and
  order.

Signed-off-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>