This commit updates the procedure for changing the hostname on arch
guests to occur in a single command. Previously, setting the hostname
and adding the value of the hostname to the /etc/hosts file was done in
two different uploads. This reduces the cycle to a single upload, making
provisioning a bit faster.
Additionally, this changes the behavior of the /etc/hosts file to:
1. Not remove localhost as an alias of 127.0.0.1
2. Prepend our custom hostname before localhost
The resulting /etc/hosts file will look something like:
127.0.0.1 my-host.example.com my-host
127.0.0.1 localhost.mydomain localhost
Tested against `terrywang/archlinux` using the following Vagrantfile:
```ruby
Vagrant.configure(2) do |config|
config.vm.box = "terrywang/archlinux"
config.vm.hostname = "banana-ramama.example.com"
config.vm.network "private_network", type: "dhcp"
config.vm.network "private_network", ip: "33.33.33.10"
config.vm.provision "file", source: "Vagrantfile", destination: "/tmp/vf"
config.vm.provision "shell", inline: "echo hi"
end
```