improve admin, add HealthFacility children inline

Improve usability of the admin view by showing additional fields, plus show all children of a Health Facility in an inline when editing it, allowing to easily follow a hierarchy of facilities.

Django 1.11 compatibility and admin improvements, package fixes

Django 1.11 compatibility.
Remove old/broken admin autocompletion code, optionally using django_extensions' ForeignKeyAutocompleteAdmin if available.
Fix MANIFEST.in file to include additional files (templates etc.)