* 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
* Create new column family for local node info
* remove DBTransaction::new reliance on DB
* KeyValueDB trait
* InMemory KeyValueDB implementation
* journaldb generic over KVDB
* make most of `ethcore` generic over KVDB
* fix json tests compilation
* get all tests compiling
* implement local store (just for transactions)
* finish local store API, test
* put everything into place
* better test for skipping bad transactions
* fix warning
* update local store every 15 minutes
* remove superfluous `{}`s
