Include unicode type for annotation value (#235)

Author: pbzweihander

aws_xray_sdk/core/utils/compat.py

@@ -6,7 +6,7 @@
 PY35 = sys.version_info >= (3, 5)
 
 if PY2:
-    annotation_value_types = (int, long, float, bool, str)  # noqa: F821
+    annotation_value_types = (int, long, float, bool, str, unicode)  # noqa: F821
     string_types = basestring  # noqa: F821
 else:
     annotation_value_types = (int, float, bool, str)