Add template "theme" feature, albeit global

would be even better to let each user session have something different, but
alas this is all-or-nothing for now

tailbone/templates/base_meta.mako

@@ -0,0 +1,17 @@
+## -*- coding: utf-8; -*-
+
+<%def name="app_title()">Rattail</%def>
+
+<%def name="global_title()">${"[STAGE] " if not request.rattail_config.production() else ''}${self.app_title()}</%def>
+
+<%def name="favicon()">
+  <link rel="icon" type="image/x-icon" href="${request.static_url('tailbone:static/img/rattail.ico')}" />
+</%def>
+
+<%def name="head_tags()"></%def>
+
+<%def name="header_logo()"></%def>
+
+<%def name="footer()">
+  powered by ${h.link_to("Rattail", url('about'))}
+</%def>