Copy-paste RPC Service class for backwards compatibility

blueprint oslo-messaging

Change-Id: Ie48de6d3636d6404316f19d73c7e8453298ecf14
Introduced rpc_compat.create_connection()

This will be used to emulate oslo-rpc API using oslo.messaging.

blueprint oslo-messaging

Change-Id: I2c1aa159132e4aad0138d4b0b7ff90eb98ed400c
Merge "Copy-paste RPC Service class for backwards compatibility"
Merge "Introduced rpc_compat.create_connection()"