Make facilitator public key configurable
FACILITATOR_PUBLIC_KEY is hardcoded in the registration helpers
flashproxy-reg-url. It won't work for any facilitator but the one at fp-facilitator.org.
It should be configurable from the command line so that you can easily test with another facilitator.
./flashproxy-reg-email --facilitator-pubkey key.asc
This configurable public key corresponds to the private key that is given to
flashproxy-reg-daemon with the