Separate migrations from util (#6690)

* separate migration from util and make its dependencies into libs:

* snappy
* kvdb
* error
* common

* renamed common -> macros

* util error does not depend on snappy module

* ethsync does not depend on util nor ethcore_error

* nibbleslice and nibblevec merged with patricia_trie crate

* removed unused dependencies from util

* util journaldb traits does not need to be public

* util_error

* fixed ethcore compile error

* ignore .swo files

* Update chain.rs

ethcore/src/client/test_client.rs

@@ -27,6 +27,7 @@ use bigint::prelude::U256;
 use bigint::hash::H256;
 use parking_lot::RwLock;
 use util::*;
+use kvdb::{Database, DatabaseConfig};
 use bytes::Bytes;
 use rlp::*;
 use ethkey::{Generator, Random};