new shelves can be given names always

Previously new shelves created when a default shelf was selected did not provide the option to create a new unique name. Now they do.
fixes #1491

bookwyrm/templates/shelf/create_shelf_form.html

@@ -7,7 +7,7 @@
 
 {% block form %}
 <form name="create-shelf" action="{% url 'shelf-create' %}" method="post">
-    {% include "shelf/form.html" with editable=shelf.editable form=create_form %}
+    {% include "shelf/form.html" with editable=True form=create_form %}
 </form>
 {% endblock %}