Improve logic used to determine if current theme supports Buefy

let settings define this per theme, but have sane defaults also

tailbone/views/master.py

@@ -252,6 +252,22 @@ class MasterView(View):
         return labels
 
     def get_use_buefy(self):
+        """
+        Returns a flag indicating whether or not the current theme supports
+        (and therefore should use) the Buefy JS library.
+        """
+        # first check theme-specific setting, if one has been defined
+        theme = self.request.registry.settings['tailbone.theme']
+        buefy = self.rattail_config.getbool('tailbone', 'themes.{}.use_buefy'.format(theme))
+        if buefy is not None:
+            return buefy
+
+        # TODO: should not hard-code this surely, but works for now...
+        if theme == 'falafel':
+            return True
+
+        # TODO: probably should not use this fallback? it was the first setting
+        # i tested with, but is poorly named to say the least
         return self.rattail_config.getbool('tailbone', 'grids.use_buefy', default=False)
 
     ##############################