Red Hat / Fedora networking template fixes

A few small fixes for Red Hat/CentOS/Fedora networking:

* Red Hat/CentOS - ensure static network changes don't update DNS. `PEERDNS=no` ensures the DNS settings (from /etc/resolv.conf) are not overwritten when we do an [ifdown/ifup cycle to apply Vagrant's changes](https://github.com/mitchellh/vagrant/blob/5e09577a766487e2671ed935050b4273575e249e/plugins/guests/redhat/cap/configure_networks.rb#L46-L49). This doesn't appear to be an issue with the Fedora templates as DNS servers are [hardcoded to Google DNS](https://github.com/mitchellh/vagrant/blob/master/templates/guests/fedora/network_static.erb#L11-L12):
* Red Hat/CentOS/Fedora - `static` is not a valid BOOTPROTO value. Valid BOOTPROTO choices include: `none`, `bootp` and `dhcp`. In the case of static network addresses `none` should be used. 

More info about te network settings these patches fix are in the [Red Hat](https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/5/html/Deployment_Guide/s1-networkscripts-interfaces.html
) and [CentOS](http://www.centos.org/docs/5/html/Deployment_Guide-en-US/s1-networkscripts-interfaces.html) docs.