CoAP dissector: Update option numbers from RFC7252

* "Accept" option: The option number was changed late in the
  specification process.
* "Proxy-Scheme" / "Size1": After including those, all option numbers
  specified in the RFC can be dissected by wireshark.

Change-Id: I1b475ac6920fd021e3217cd3b44c173d264a5298
Reviewed-on: https://code.wireshark.org/review/4123
Reviewed-by: Evan Huus <eapache@gmail.com>
Petri-Dish: Evan Huus <eapache@gmail.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Michael Mann <mmann78@netscape.net>