Calling decode('utf-8') on the template rendering shouldn't be necessary

All tests still pass, and it fixes #305

compressor/templatetags/compress.py

@@ -107,7 +107,7 @@ class CompressorMixin(object):
             rendered_output = self.render_output(compressor, mode, forced=forced)
             if cache_key:
                 cache_set(cache_key, rendered_output)
-            return rendered_output.decode('utf-8')
+            return rendered_output
         except Exception:
             if settings.DEBUG or forced:
                 raise