demosite: update demosite package for create/populate

* Changes from invenio_demosite to invenio_demosite.base

Signed-off-by: Javier Martin Montull <javier.martin.montull@cern.ch>
installation: MANIFEST template fix

* Fixes the MANIFEST template to include all jsonext configuration
  files.

Co-authored-by: Esteban J. G. Gabancho <egabancho@gmail.com>
Signed-off-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>
search: change in templates inheritance schema

* Makes index_base.html and results_base.html
  inherit from searchbar_frame.html instead of
  page base.html to share the search-bar.

Signed-off-by: Kamil Neczaj <kamil.neczaj@cern.ch>
Reviewed-by: Javier Martin Montull <javier.martin.montull@cern.ch>
search: search bar adaptation to typeahead 0.10

* Makes the parser configurable.

Signed-off-by: Kamil Neczaj <kamil.neczaj@cern.ch>
Reviewed-by: Javier Martin Montull <javier.martin.montull@cern.ch>