Resource::find_object can go into infinite loop/recursion

[tadeboro]

Steps to reproduce:

1. Start a mock server (trying this on a real server is not the best idea).
2. Open python REPL and run redfish_client.connect("http://localhost:8000", "user", "pass").Systems.Members[0].find_object("bad").

Expected result: find_object reports that "bad" cannot be found.

Actual result: find_object recursively scrapes the whole Redfish API, goes into a loop and eventually dies.