Bug 917047: Remove the security.enable_md5_signatures pref, r=briansmith

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extra : rebase_source : ae721bc7f91b399e61c2efb869e15ab902c810e0
Bug 945195: Do insecure fallback from TLS 1.0 to SSL 3.0 when we receive a FIN during the initial handshake, r=honzab

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extra : rebase_source : d10091aea21f7d552f682d54383bf43ece7633ed