fixes Bug 1077234: restore config_path & values_source_list to app framework

the older app framework allowed apps to define their own config_path and values_source_list.  None of the apps in the socorro package actually  used the feature.   The new SocorroApp framework removed the feature.  I didn't think to look outside the package to the wsgi directory.   It turns out that the .wsgi files use the 'config_path' and  the .py files used both 'config_path' and 'values_source' list.  It didn't show up in unit or integration tests because they all use the internal CherryPy web servers.

This PR restores both 'config_path' and 'values_source_list' to the app framework.