Integrate C3T Pico instance with Helios

[bktiel]

Integrate live pico instance at https://pico.c3t.eecs.net with helios.

Two goals:

1. Make Helios the "SSO" solution. Integrate Helios users with the pico's database such that generating an account on Helios creates a matching one on Pico. Furthermore, modify pico to accept Helios cookies as valid.
2. (easier) add link to pico to Helios landing for quick access

A stretch goal is figuring out a way for helios to track solved challenges on pico and prompt user for writeups on those specific challenges. This ties to a larger goal of having writeups tied to challenges enumerated in competition defs (tbd)