Update ELB creation code to reflect new SSLNegotiationPolicyType behavio...

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AWS recently changed the behavior of the SSLNegotiationPolicyType component of the createListener call, so that one can longer simply specify all of the ciphers that should be _disallowed_ from the standard slate of available policies. Now one must specify which ciphers should be _allowed_ as well. This was breaking automated ELB creation in ironfan, and this pull request fixes it by adding the `elastic_load_balancer` setting called `allowed_ciphers`, and by setting (new) reasonable defaults for both `allowed_ciphers` and `disallowed_ciphers`