Execution: remove manager package/notion to simplify and improve structure
(we only have one manager), remove pipe (busywork and not really a
pipe),
use account, blockchain, and state types and interfaces throughout.
TxCache, BlockCache, and State. Encapsulate Tx execution in Executor
interfaces. Implement Tendermint 0.12 ABCI app. Refactor tests to
support new interfaces and make minor improvements to them.

EVM: Use single definitions of state from account packages and use immutable
Account instead of separate vm accounts. Emit vm debug in standard
logging. Reorganise package. Use strongly typed Address.

Signed-off-by: Silas Davis <silas@monax.io>