No Bug - fixed crisis where classes in __main__ aren't imported correctly

this is a fall forward patch to the original ```one-app-to-rule-them-all``` PR where there was problem with the code to make app invocation backwards compatible.  

The problem was that classes imported with in the module serving as "__main__" do report the actual module name in which they are defined.  This caused confusion in configman where in attempting to reconstruct the actual module name failed when the CWD was not at the root of the socorro package.

this patch corrects the problem by searching through the PYTHONPATH (via sys.path) for the proper module from which the class was actually defined.