Simplify UASF Activation Logic, and update specification.

[da2ce7]

Updated BIP 148 Activation Logic, as the timeout of this BIP is completely redundant.

[da2ce7]

@shaolinfry please review.

[da2ce7]

I'm going to withdraw this pull request, as dealing with the logic for a very slow hash-rate after the enforced period starts.

[shaolinfry]

In case you arent aware of the discussions, the reason the date was moved to Aug 1 was exactly to handle a ridiculous drop in hashrate, regardless of how unlikely.

[dooglus]

There's no point in having this UASF active after the SegWit activation period has timed out.

From Bitcoin's src/chainparams.cpp:

    // Deployment of SegWit (BIP141, BIP143, and BIP147)
    consensus.vDeployments[Consensus::DEPLOYMENT_SEGWIT].bit = 1;
    consensus.vDeployments[Consensus::DEPLOYMENT_SEGWIT].nStartTime = 1479168000; // November 15th, 2016.
    consensus.vDeployments[Consensus::DEPLOYMENT_SEGWIT].nTimeout = 1510704000; // November 15th, 2017.