Limit months shown to current and past

Matches what we do on the usage page. No need to see months in the
future because there’s no way you’ll have sent any messages in those
months, unless you’re Marty McFly.

app/templates/views/dashboard/monthly.html

@@ -36,28 +36,30 @@
         ],
         field_headings_visible=False
       ) %}
-        {% call row_heading() %}
-          {{ month.name }}
-        {% endcall %}
-        {% for counts, template_type in [
-          (month.email_counts, 'email'),
-          (month.sms_counts, 'sms')
-        ] %}
-          {% call field(align='left') %}
-            {{ big_number(
-              counts.requested,
-              message_count_label(counts.requested, template_type, suffix=''),
-              smallest=True,
-            ) }}
-            {% if counts.requested %}
-              <span class="{{ 'failure-highlight' if counts.show_warning else '' }}">
-                {{ counts.failed }} failed
-              </span>
-            {% else %}
-              –
-            {% endif %}
+        {% if not month.future %}
+          {% call row_heading() %}
+            {{ month.name }}
           {% endcall %}
-        {% endfor %}
+          {% for counts, template_type in [
+            (month.email_counts, 'email'),
+            (month.sms_counts, 'sms')
+          ] %}
+            {% call field(align='left') %}
+              {{ big_number(
+                counts.requested,
+                message_count_label(counts.requested, template_type, suffix=''),
+                smallest=True,
+              ) }}
+              {% if counts.requested %}
+                <span class="{{ 'failure-highlight' if counts.show_warning else '' }}">
+                  {{ counts.failed }} failed
+                </span>
+              {% else %}
+                –
+              {% endif %}
+            {% endcall %}
+          {% endfor %}
+        {% endif %}
       {% endcall %}
     </div>
   {% endif %}