global: super call addition to SmartDict

• BETTER Adds super(SmartDict, self).init call in the init method in SmartDict to be able to make multiple inheritance in Record class in invenio-records and be able to call both parent's init.

Signed-off-by: Łukasz Chrząszcz <l.chrzaszcz@gmail.com>
Reviewed-by: Esteban J. G. Gabancho <esteban.gabancho@gmail.com>