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: browse.html inheritance changed

* Inherits searchbar_frame.html to get shared
  searchbar code.

Signed-off-by: Kamil Neczaj <kamil.neczaj@cern.ch>
formatter: TypeError fix in record template

* Fixes "TypeError: %d format: a number is
  required, not dict" in function
  render_record_footer in
  Default_HTML_brief_macros.tpl.

Signed-off-by: Kamil Neczaj <kamil.neczaj@cern.ch>
search: code clean-up, comments, documentation

* Improves code organization in
  helpers_base.html.

Signed-off-by: Kamil Neczaj <kamil.neczaj@cern.ch>
search: fix for browse button

Signed-off-by: Kamil Neczaj <kamil.neczaj@cern.ch>