Filter on date range

See merge request !86

Remove binding of query parameter with filter so we can filter on more than one
and display a single template with multiple filters

Make terms optional in ItemSerializer

See merge request !85

Fix 'This field is required' errors. No idea why we didn't see this before.

First stab at some location coverage.

See merge request !84

CSS styling and template reorganisation

See merge request !80

This template is still broken (data-view URL). Not sure if we need it

Add the upload form to the base template

See merge request !83