fix issue : can't irerate on a dict in python3

[Obimka]

File : rbac/default_role_manager/role_manager.py
Line : 15~16

 def has_role(self, name):
        return name in self.all_roles.keys()

Error : In python3 you can't iterate on a dict

Fix :

-        return name in self.all_roles.keys()
+        return name in list(self.all_roles.keys())

see : #1