BibFormat: QR-code format element

* Adds QR-code bibformat element that links to the current
  record. (closes #1441)

* Requires Python modules qrcode (Python 2.5+) and PIL/Pillow.

Tested-by: Tibor Simko <tibor.simko@cern.ch>
BibSched: parse_runtime_limit() tests fix

* Fixes bug in parse_runtime_limit tests which would give a limit
  range in the past, when expected returned ranges should always
  either contain the current time or being in the future.
  (closes #1432)

Tested-by: Jiri Kuncar <jiri.kuncar@cern.ch>
BibField: bug fixes when using decorators

* Fixed @parse_first and depends_on behaviour.  (closes #1502)

Signed-off-by: Esteban J. G. Gabancho <esteban.gabancho@cern.ch>
Tested-by: Tibor Simko <tibor.simko@cern.ch>
Merge branch 'maint-1.1'

* maint-1.1:
  BibSched: parse_runtime_limit() tests fix
OAIRepository: CFG_OAI_REPOSITORY_MARCXML_SIZE

* Increases CFG_OAI_REPOSITORY_MARCXML_SIZE from 100 to
  1000 in order to reduce the overhead due to bibupload
  creation.

Reviewed-by: Tibor Simko <tibor.simko@cern.ch>
BibField: new @persistent_identifier "decorator"

* New "decorator" inside the config file that allows to specify
  when a json key is used as persistent identifier and its order
  of preference.  All json keys that should be considered as persistent
  identifier are stored inside the calculated field
  _persistent_identifiers_keys.  (closes #1500)

* New getter to provide a subset of the record containing all
  the persistent identifiers, based on _persisitent_identifiers_keys

Signed-off-by: Esteban J. G. Gabancho <esteban.gabancho@cern.ch>
Tested-by: Tibor Simko <tibor.simko@cern.ch>
Merge branch 'maint-1.1'

* maint-1.1:
  OAIRepository: CFG_OAI_REPOSITORY_MARCXML_SIZE
Merge branch 'master' into next

* master:
  BibField: new @persistent_identifier "decorator"
  OAIRepository: CFG_OAI_REPOSITORY_MARCXML_SIZE
  BibField: bug fixes when using decorators
  BibSched: parse_runtime_limit() tests fix
  BibFormat: QR-code format element