[#296] more integration tests for multisig

1) add scenarios for multisig 2-of-2, 1-of-3, 2-of-3 and 3-of-3. They are same scenario as for simplesig and mutltisig 1-of-2. See https://github.com/JahPowerBit/counterpartyd/blob/develop/test/fixtures/scenarios.py#L23
2) add comparison between multisig scenarios dump and simplesig scenario dump. We verify if the sql dump is exactly the same except for addresses and hashes. See https://github.com/JahPowerBit/counterpartyd/blob/develop/test/util_test.py#L217 and https://github.com/JahPowerBit/counterpartyd/blob/develop/test/integration_test.py#L20
yes, it's a negative change quantity, because I change the amount of the burn (from 0.62 to 1) so the first utxo was not enough, then it takes also the following utxo (https://github.com/JahPowerBit/counterpartyd/blob/develop/test/fixtures/scenarios/multisig_1_of_2.log#L166)