Modify the sfu_api plugin to use the existing canvas oauth system.

override api_request? to always return true

check authorized_action in user method

force api routes to JSON

not all routes require authentication

remove unused require statements

switch from render :text to render :json

add 404s where appropriate

allow unrestricted access to /users/:id/terms (only)

downcase the sis_id, just in case

remove requires_auth_token? method

return to simple api_request? method

always return true

make .../user/:sfu_id/uuid return JSON instead of text