Change "reusability" to "type" for invites

- This makes the choice much clearer
- Allows for less generic terms in the table
- Future extensibility \o/

snikket_web/templates/admin_edit_invite.html

@@ -14,7 +14,7 @@
 		<dd>{{ invite.expires | format_date }}</dd>
 		<dt>{% trans %}Link{% endtrans %}</dt>
 		<dd>{% call showuri(invite.landing_page) %}{% endcall %}</dd>
-		<dt>{% trans %}Reusability{% endtrans %}</dt>
+		<dt>{% trans %}Invitation type{% endtrans %}</dt>
 		<dd>{% if invite.reusable %}{% trans %}This invitation link can be used arbitrarily often, until it expires, is revoked or a service-wide user limit is reached.{% endtrans %}{% else %}{% trans %}This invitation link can only be used once and is then depleted.{% endtrans %}{% endif %}</dd>
 		{%- set ngroups = invite.group_ids | length -%}
 		{%- if ngroups > 1 -%}