Move ip address processing from awk to ruby, add spec
Ignore ipv6 addresses, use "IPAddr" ruby library
Add spec for invalid ip addresses
Raise error if "hostname -I" doesn't return addresses
Install bundler 1.5 for vagrant
Minitest::Spec instead of rspec to assert raising error
 Fix spec description
Merge pull request #65 from njam/hostname-ipv4

Ignore IPv6 addresses in read_host_visible_ip_address
switch to assignment style enable

matches more closely with general vagrant styyle

backwards compatible with old methods