persistentid: add function to create url

* Adds a function that for a given persistent identifier will
  try to create a URL to a resolver.
persistentid: fix ISSN validation issue

* Fixes an issue where an 8-character non-ISSN string would cause an
  exception.

Signed-off-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>
bower: upgrade ckeditor to version 4

* Upgrades CKEditor to version 4 in bower requirements.
apikeys: add option to disable signing

* Adds option to disable need for signing an API request.
legacy: fix issue with undefined variables

* Fixes issue with undefined variables.
records: add configurable breadcrumb title

* Fixes an issue where the breadcrumb did not display the record title,
  due to using a wrong jsonalchemy field.
searchengine: fix restricted collection search

* Fixes an issue where a guest user could not search for records
  in a restricted collection authorized for to the guest user.
base: add pre-template-render signal

* Adds signal that can be sent from views prior to
  a template being rendered. This allows simple customizations
  of the template context.