Policy equality fails for binding list order

[chingor13]

The binding list order should not matter for the equivalence of Policy objects:

 @Test
 public void testPolicyOrderShouldNotMatter() {
 Role role1 = Role.of("role1");
 Identity identity1 = Identity.user("user1@example.com");
 Role role2 = Role.of("role2");
 Identity identity2 = Identity.user("user2@example.com");
 Policy policy1 = Policy.newBuilder()
 .addIdentity(role1, identity1)
 .addIdentity(role2, identity2)
 .build();
 Policy policy2 = Policy.newBuilder()
 .addIdentity(role2, identity2)
 .addIdentity(role1, identity1)
 .build();
 assertEquals(policy1, policy2);
 }

[chingor13]

In #110, we switched the data model from a Map to a List and List equality is order dependenct