Revert "Remove trailing ? from Github avatar URL in the hopes that this fixes the seg"

This reverts commit 6905de3def0696220adeccc108e98ebd357fdf03.
Revert "Remove extension whitelist, as further heroku debugging effort."

This reverts commit e40d89c3602292230ec43c2b2af29f8d1a70c9cc.
I'm going to keep fiddling bits until I find a way around that damn seg
fault.  This is my life's mission now. NEVER GIVE UP. Never.