Add tests for ip command output
Add _parse_ip subroutine

Extracts the following information by parsing ip command output for a
single network interface:
- MAC addess
- IP address
- CIDR prefix
- broadcast address
Converts the netmask from CIDR to dotted decimal notation before return.
Note: currently works with IPv4 only.
Make get_network_devices try to use ip command if available
Make get_network_configuration try to use ip command if available
Merge remote-tracking branch 'ferki/ip' into development