Start reworking invoice things

RIGS/templates/partials/event_table_colour.html

@@ -0,0 +1,9 @@
+class="{% if event.cancelled %}
+            text-muted table-secondary
+        {% elif event.authorised and event.risk_assessment_edit_url and event.mic %}
+            table-success
+        {% elif not event.is_rig %}
+            table-info
+        {% else %}
+            table-warning
+        {% endif %}"