Z-Wave S2 security framework support

[matt (support)]

We have on our development schedule (no ETA of course) to improve Indigo to support S2 protocol pairing. Currently, Indigo always does S0 for compatibility – a lot of security modules being used with Indigo unfortunately don't support S2. After S2 pairing is supported we are also going to improve Indigo so that whenever a potentially insecure S0 pairing process is about to occur (the only time at which there is a known vulnerability using S0) the user is first prompted for approval. This will help mitigate the problem a bit but still allow compatibility with older modules that don't support S2.