Ship the email templates as package_data

move the example email templates into the synapse package so that they can be
used as package data, which should mean that all of the packaging mechanisms
(pip, docker, debian, arch, etc) should now come with the example templates.

In order to grandfather in people who relied on the templates being in the old
place, check for that situation and fall back to using the defaults if the
templates directory does not exist.

synapse/res/templates/room.html

@@ -0,0 +1,33 @@
+<table class="room">
+    <tr class="room_header">
+        <td class="room_avatar">
+            {% if room.avatar_url %}
+                <img alt="" src="{{ room.avatar_url|mxc_to_http(48,48) }}" />
+            {% else %}
+                {% if room.hash % 3 == 0 %}
+                    <img alt="" src="https://vector.im/beta/img/76cfa6.png"  />
+                {% elif room.hash % 3 == 1 %}
+                    <img alt="" src="https://vector.im/beta/img/50e2c2.png"  />
+                {% else %}
+                    <img alt="" src="https://vector.im/beta/img/f4c371.png"  />
+                {% endif %}
+            {% endif %}
+        </td>
+        <td class="room_name" colspan="2">
+            {{ room.title }}
+        </td>
+    </tr>
+    {% if room.invite %}
+        <tr>
+            <td></td>
+            <td>
+                <a href="{{ room.link }}">Join the conversation.</a>
+            </td>
+            <td></td>
+        </tr>
+    {% else %}
+        {% for notif in room.notifs %}
+            {% include 'notif.html' with context %}
+        {% endfor %}
+    {% endif %}
+</table>