legacy: new webinterfaces registry
legacy: new webinterfaces registry

* Adds new registry for legacy webinterfaces.  (closes #2239)

* NOTE Adds PendingDeprecationWarning for *ALL* legacy pages.

Signed-off-by: Jiri Kuncar <2bdffcb416fed3002465740d19a053a39918cbe5@cern.ch>

inveniosoftware/invenio-base,tiborsimko/invenio-base,inveniosoftware/invenio-base,tiborsimko/invenio-base