* db refactor in progress, refactored kvdb

* kvdb refactor

* removed unused RwLock

* removed unused RwLock

* BlockChainDatabase

* db refactor in progress

* implemented BlockProvider for newdb

* fixed compiling

* newdb TransactionMeta

* newdb tests

* reopen tests for newdb

* replaced old db with new db

* chain_verifier uses new db

* sync module uses refactored db

* check double spends in verification layer

* added Forkable trait to satisfy resolving recursive types by compiler

* new db regtests in progress

* fixed verification and sync unit tests

* fixed miner and rpc unit tests

* implemented fmt::Debug for few structs

* removed commented out code

* fixed bencher target

* removing commented out code, polishing db_refactor pr

updated mio to 0.6.6, use tokio_io::io instead of deprecated tokio_core::io

mio 0.6.5

updated futures and rayon crate

update the rest of dependencies

updated jsonrpc modules and serde from 0.8 to 0.9

Updated dependencies + removed specific-commit version reference to tokio_core

Fixed `Script::find_and_delete` arguments

Send ping requests on timeout

Pass version message to sync when starting sync session

Temporary switched to github version of tokio-core

Get rid of separate cpu pool in sync

Fix build

Updated dependencies

Implemented blocknotify option

Remove debug print from sync

Fixed clippy warnings in sync