[AWS|ELB] use ['Policies']['Proper'] as the canonical mock policy store
[AWS|ELB] remove unused bits
[AWS|ELB] check the result of describe_load_balancer_polices for each policy by name
[AWS|ELB] test that describe_load_balancers mocks properly formats policy results
[AWS|ELB] restore policy.cookie and policy.expiration methods
Merge pull request #2036 from mikehale/aws-elb-more-updates

[AWS|ELB] fix and mock improvements