Force tag value to be string before rendering (#66)

Fixes #65

Author: jayvdb

classytags/core.py

@@ -148,7 +148,7 @@ def render(self, context):
         items = self.kwargs.items()
         kwargs = dict([(key, value.resolve(context)) for key, value in items])
         kwargs.update(self.blocks)
-        return self.render_tag(context, **kwargs)
+        return str(self.render_tag(context, **kwargs))
 
     def render_tag(self, context, **kwargs):
         """