utils/types: implement __ne__ for level

This should have been handled by the @total_ordering decorator, but
isn't due to

        https://bugs.python.org/issue25732

(briefly, total_ordering is back-ported from Python 3, where the base
object provides the default implementation of __ne__ based on __eq__, so
total_ordering did not override it; this, however does not happen in
Python 2).

Also update unit tests to catch this edge case.

wa/utils/types.py

@@ -569,6 +569,15 @@ class level(object):
         else:
             return self.value < other
 
+    def __ne__(self, other):
+        if isinstance(other, level):
+            return self.value != other.value
+        elif isinstance(other, basestring):
+            return self.name != other
+        else:
+            return self.value != other
+
+
 
 class _EnumMeta(type):