Define a standard way to specify the chaincode package id and server address across sample chaincodes

[lehors]

Samples are currently inconsistent in how the chaincode package id is specified, e.g., CHAINCODE_ID vs CORE_CHAINCODE_ID_NAME, CHAINCODE_SERVER_ADDRESS vs CC_SERVER_PORT vs CCAAS_SERVER_PORT... We should define one set of variables to be used consistently across all samples.