add encryption and transport parameter to sip.pp

transport: specify array of protocols to use for signaling.
           Possible values are udp, tcp, tls

encryption: specify if you want to use srtp
Add support for all the other debian packages for language files.

This enables support for more languages and should let people install
language sounds in a specific encoding.
Add new language strings to documentation.
Merge remote-tracking branch 'trefzer/sip_secure'
Add some documentation about setting up SIP encryption.

Thanks to trefzer for the info on which settings need to be set in order
to get things encrypted.