Expose WebSocketServerFactory's externalPort arg 

externalPort allows a WebSocketServer to run behind a reverse
proxy. Exposing it allows WampServer to run behind a reverse
proxy as well.
Merge pull request #122 from ewollesen/master

Expose WebSocketServerFactory's externalPort arg
Added optional Salt to WAMP-CRA
Fixed incorrect prefix and changed subscribe and publish topics to align with examples on server side.
Merge pull request #123 from cachedout/master

Fix for Python client in custom PubSub example
Renamed serverExtra -> authsalt
fixes issue #118
Merge branch 'master' of github.com:tavendo/AutobahnPython
document dependencies in README, issue #116
Use pbkdf2 for password salting
Fixed incorrect prefix and changed subscribe and publish topics to align with examples on server side.
Renamed serverExtra -> authsalt
fixes issue #118
document dependencies in README, issue #116
Use pbkdf2 for password salting
Merge remote-tracking branch 'origin' into wamp_scra
Merge pull request #124 from klemmster/wamp_scra

Wamp scra
Merge branch 'master' into symmetric_rpc