Fix assumption that the network interface is always 'eth0'. It is not the case
on newer Linux distros that are now adopting the device name.

Set Squid version to be 3.2 on Fedora; this turns off directives in the template
that are now built into Squid and cause startup errors if repeated.
Add conditionals around Squid 3.2, and also add IPv6 addresses to the default acl.
Merge pull request #23 from opscode-cookbooks/juliandunn/fix-assumptions

fix assumptions that cause breakage