This answering machine can be connected to a Fritz!Box or other VOIP
router as IP phone.

The PhoneBlock-AB cloud answering machine is implemented as external
VOIP device that registers at the customers router. To find the router's
IP address PhoneBlock-AB provides a built-in DynDNS service. This can be
used, if the has no domain name registered and no otherwise configured
DynDNS service.

Extracted PhoneBlock API to separate module phoneblock-shared. Only
accept calls that have sufficient PhoneBlock votes. Added service
configuration file to add PhoneBlock as Linux systemd service.

Added version information to startup.

The answering machine must support different audio formats depending on
the remote receiver.