* remove assetDataUtils everywhere
* export IAssetDataContract from @0x/contract-wrappers to allow @0x/instant to decode asset data synchronously
* export generic function `decodeAssetDataOrThrow` and add ERC20Bridge support
* export `hexUtils` from order-utils instead of contracts-test-utils
* generate wrappers in @0x/contract-wrappers and delete abi-gen-wrappers
* trim exports from contract-wrappers
* separate contract-wrappers tests to get rid of dependency cycle
* remove dummy token contracts
* temporarily skip coordinator test until we can upgrade coordinator server