CTF Authentication Timeout

[calebstewart]

The ctfd provider doesn't currently handle session timeouts properly, and results in JSON exceptions. The provider should recognize the timeout and attempt re-authentication, however it doesn't. I can probably wrap this into the generic CTFProvider interface by raising an authentication exception in the individual providers and having the base CTFProvider retry authentication appropriately.

This may also propagate to the pico provider as well. I haven't looked into it yet.