Fix bug in ValidatedEmail method __eq__() (#66)

Check parameter `other` is an instance of ValidatedEmail before
checking all its members are equal to self's members.

Author: yassam

email_validator/__init__.py

@@ -142,6 +142,8 @@ def __getitem__(self, key):
 
     """Tests use this."""
     def __eq__(self, other):
+        if not isinstance(other, ValidatedEmail):
+            return False
         return (
             self.email == other.email
             and self.local_part == other.local_part