go-kosu: Use MultiStore

[gchaincl]

Overview

Use MultiStore engine from cosmos-sdk

Description

Replaces the state management using the right tool for the job +1
Some other minor changes are included here.

[hrharder]

Awesome! I will test this out today @gchaincl. Yesterday i was able to recreate the issue in the test-net with nodes not getting the same AppHash for blocks (resulting in consensus failure) so hopefully this resolves that. Did you get to trying it out in the docker-compose testnet yet?

[hrharder]

Merge whenever you feel is ready @gchaincl. i will try to spend some time investigating the rebalance issue

[hrharder]

I believe I have fixed the rebalance issue (see fix/go-kosu/rebalance-issue)

Was able to get it to go up to ~10 in round number before I turned it off.

I believe the issue was that all 4 rebalance transactions were getting executed instead of one, the reason being DeliverTx assumed all Tx's that passed CheckTx are still valid, even though they may not be. So by running CheckTx again before modifying the state, we can make sure the transaction from the mempool is still valid.

@gchaincl I also set the initial round info in the Store during my debugging, and I'm not sure if that contributed to the fix, but I left it.

Feel free to merge my branch in to this, or just add the additional checkTx call here.

[gchaincl]

Great news! I remember I was checking it twice but then I removed it cause I thought it was duplicated. Thanks for finding the problem!