Ethereum and Fabric worker and registry implementations differ

[danintel]

Whlie documenting the Ethereum and Fabric SDKs I noticed the implementations differ.

For these methods for Etherum, the return code is: Transaction receipt on success or None on error. For Fabric, the return code is: ContractResponse.SUCCESS on success or ContractResponse.ERROR on error.

The methods where the implementation differs are:

Methods registry_add(), registry_update(), registry_set_status() File sdk/avalon_sdk/ethereum/ethereum_worker_registry_list.py File sdk/avalon_sdk/fabric/fabric_worker_registry_list.py

Methods worker_register(), worker_update(), worker_set_status() File sdk/avalon_sdk/ethereum/ethereum_worker_registry.py File sdk/avalon_sdk/fabric/fabric_worker_registry.py