* Rename RegistryInfo -> RegistryInfoDeprecated
* Add BlockId parameter to Registrar::get_address and RegistrarClient::call_contract
* Remove RegistrarClient::Call (use async for now); add RegistrarClient::get_address
* Remove Registrar type in favour of naked trait
* Use CallContract trait bound instead of separate call_contract method
* Make RegistrarClient::get_address and URLHint::resolve synchronous
* RegistrarClient::get_address: return check if address is zero
* Modify RegistryInfo::registry_address to take &str
* return Result from RegistryInfo::registry_address
* Replace RegistryInfo with RegistrarClient
- Modifed RegistrarClient::registrar_address to return Option
- Removed BlockChainClient::registrar_address
* Fix other build configs
* Fix unit test builds
* Remove local RegistrarClient type from run::execute_impl
* Remove registrar.json from ethcore
* Formatting/line breaks
* Update RegistrarClient docs, remove explicit lifetime
* Weak ref to ethcore client from hash fetch client
* Fix unit tests
