Revert "Submit answers to their server"

This reverts commit acf2d5aa4b4b83c9d999ebf42486a2658b2a1f26.

Conflicts:

	puzzles/coinheist.py
	puzzles/views.py
Use :thumbsup: instead of gravatar hack
Fix Humbug account creation
Humbug -> Zulip in user-visible text
Add a Cancel button to Answer submission form
Add a Cancel button to Uploade submission form