Make parity-bitcoin usable for spv validation

- In this PR I extract from the crate `db` to the new `storage` crate all traits that is not specifically related to the concrete implementation of database. So I now can use `verification` crate without `rocksdb` dependency.

- Also I modify the `HeaderAcceptor` so that can be constructed without the private `BlockDeployments`.

Bitcoin Cash: OP_DIV and OP_MOD implementation

Bitcoin Cash: OP_CAT implementation

Replace try! with ? in script

Removed AsciiExt import

Update log 0.3 -> 0.4, env_logger 0.4 -> 0.5

Update rand rand 0.3 -> 0.4

Bitcoin Cash: hardcode DAA HF height

Remove segwit2x mentions

Fixed BoxFuture-related warnings

updated dependencies

Hardcode SegWit deployment

Suport Bitcoin Cash difficulty adjustment hardfork