Rearrange.
Code uniformity.
Add M2Crypto check to flashproxy-reg-url.

Like in flashproxy-reg-email.
Prototype registration over App Engine

See #8860 for details.
App Engine app handling /ip and /reg.

Works with the prototype described in #8860
Override Host header.

Make connection to www.google.com but access the
flashproxy-reg.appspot.com domain.
Return string from excepted get_external_ip.
Use URL.Path
Error checking and diagnostics.
I'm guessing these extra parens aren't needed.
go fmt.
Code uniformity.
Command-line parameters are optional in flashproxy-reg-appspot.
Split out if block for flashproxy-reg-appspot.
Remove unused facilitator_url.
Add -4 and -6 options to flashproxy-reg-appspot.
Make flashproxy-reg-appspot call flashproxy-reg-url.

Rather than do all the crypto itself.
Abstract Host substitution.
Certificate pinning for flashproxy-reg-appspot.
Error message formatting.