BibCirculation: email ID changes and test fixes

* User notification email ID changes.

* Passing regression tests.  (closes #1479)

Tested-by: Tibor Simko <tibor.simko@cern.ch>
installation: fix for jQuery hotkeys add-on URL

* Uses stable version of jQuery hotkeys plugin from
  invenio-software.org.  (closes #1507)

Reported-by: Theodoropoulos Theodoros <theod@lib.auth.gr>
Co-authored-by: Javier Martin Montull <javier.martin.montull@cern.ch>
Tested-by: Tibor Simko <tibor.simko@cern.ch>
BibFormat: skip hidden icons in OpenGraph image tag

* No need to list icons marked as "HIDDEN", as they are anyway
  not displayed.

Reviewed-by: Tibor Simko <tibor.simko@cern.ch>
Merge branch 'maint-1.1'

* maint-1.1:
  BibFormat: skip hidden icons in OpenGraph image tag
  installation: fix for jQuery hotkeys add-on URL
WebAccess: OpenID and OAuth authentication

* Introduces OpenID and OAuth external authentication plugins.

* Support out of the box several authenticatio providers (including
  Google and Facebook).  (addresses #1124)

* Merge note: this commit is exactly the one provided by Alper.  All
  amendments will be available in the next commit.

Reviewed-by: Samuele Kaplun <samuele.kaplun@cern.ch>
WebAccess: ORCID support

* Introduces support for OAuth2-based ORCID authentication by exploiting
  the external authentication support to OpenID/OAuth1/OAuth2 introduced
  with the previous commit.

* Amended previous commit by cleaning up INSTALL guide and root-level
  Makefile.am, introduced configuration of providers in invenio(-local).conf.

* In the previous commits, the new provided plugins were implemented
  assuming to be instantiated per-every request, while each plugin
  is instantiated only upon server loading and can't hence share
  request-oriented information. For this reason a new attribute called
  "g" (mimicking upcoming Flask global "g" proxy) to the req object.
  (closes #1124)

Tested-by: Tibor Simko <tibor.simko@cern.ch>
Merge branch 'master' into next

* master:
  WebAccess: ORCID support
  WebAccess: OpenID and OAuth authentication
  BibFormat: skip hidden icons in OpenGraph image tag
  installation: fix for jQuery hotkeys add-on URL
  BibCirculation: email ID changes and test fixes

Conflicts:
	Makefile.am
	config/invenio.conf
	modules/miscutil/lib/Makefile.am
	modules/miscutil/lib/inveniocfg.py
	modules/webaccess/lib/Makefile.am
	modules/webstyle/lib/webinterface_handler_wsgi.py