Split out rendering of this-page component in falafel theme

it's possible a template may need to override that

tailbone/templates/themes/falafel/base.mako

@@ -452,9 +452,7 @@
             % endfor
         % endif
 
-        <this-page
-           v-on:change-content-title="changeContentTitle">
-        </this-page>
+        ${self.render_this_page_component()}
       </section>
 
       ## Footer
@@ -539,6 +537,12 @@
   ${tailbone_autocomplete_template()}
 </%def>
 
+<%def name="render_this_page_component()">
+  <this-page
+    v-on:change-content-title="changeContentTitle">
+  </this-page>
+</%def>
+
 <%def name="render_navbar_end()">
   <div class="navbar-end">
     ${self.render_user_menu()}