Merge pull request #348 from JahPowerBit/develop

Fix holder_count for dividend fee + add get_holder_count in API
mempool regression
Merge pull request #349 from JahPowerBit/develop

Check for consensus in list of transactions
Merge pull request #351 from JahPowerBit/develop

[#65] add unit tests for bounds values
Travis CI Slack integration
[#235] fast initial synchronisation