Create Threat Model documentation

[taoeffect]

Some important considerations:

• Sybil attacks preventing seeing updates, e.g. revoked certs
  • Mitgations: check network hash rate. Make sure we're actually getting blocks every X min (whatever the protocol specifies).
• Everything here: https://en.bitcoin.it/wiki/Weaknesses#Might_be_a_problem

--- Want to back this issue? **[Post a bounty on it!](https://www.bountysource.com/issues/4703504-create-threat-model-documentation?utm_campaign=plugin&utm_content=tracker%2F528702&utm_medium=issues&utm_source=github)** We accept bounties via [Bountysource](https://www.bountysource.com/?utm_campaign=plugin&utm_content=tracker%2F528702&utm_medium=issues&utm_source=github).

[taoeffect]

Obviously: malicious or compromised DNSChain server.