Remove a Python 2.7 dependency from flashproxy-reg-appspot.

The error was:
Failed to get external IP address: PinHTTPSConnection instance has no attribute 'source_address'
The documentation for httplib says this member was added in Python 2.7.

I discovered the problem while testing the 3.x pluggable transports
bundles for Mac OS X. Because of the way M2Crypto is cross-compiled,
running the flashproxy client programs requires Python 2.6. Failure to
run flashproxy-reg-appspot means that the slower flashproxy-reg-email
would be used instead.
portmap seems to be rpcbind now.

# apt-get remove portmap
Reading package lists... Done
Building dependency tree
Reading state information... Done
Note, selecting 'rpcbind' instead of 'portmap'
- fix minor typo via pylint