Streamline char encoding on squeeze and wheezy

We need to make sure that we have a consistent `LANG` env setting across nodes for puppet / puppetmaster not to freak out on illegal characters..

I first observed this on a wheezy machine connected to a squeeze master where the node kept throwing
```
Error: /Stage[main]/Puppet::Module::Stdlib/Puppet::Module[puppetlabs-stdlib]/Exec[puppet module install puppetlabs-stdlib]: Could not evaluate: invalid byte sequence in US-ASCII
Error: Could not prefetch package provider 'apt': invalid byte sequence in US-ASCII
```