Do not inherit BaseException #426
Description
(twilio.base.obsolete.ObsoleteException](1bf8807#diff-a6f3daa0f60d54c1113e431cda41d132R5) is inheriting from BaseException, which is for fatal system errors and not intended to by extended by user code. The class should inherit from Exception. This is preventing the exception from being caught cleanly by error logging code.
Additionally, the obsolete_client code is making debugging of issues much harder than it should be, because it delays the error from import time to run time. I would much rather get an ImportError when trying to import something that has been removed.