Sanitise type

[ekohl]

I was installing a new squid proxy with some acl rules. One of these rules was the following

squid::acl{'url':
   type    => 'ssl::server_name',
   entries => ['.foo.bar'],
}

This returned an Puppet error

Error: Evaluation Error: Error while evaluating a Function Call, Order cannot contain '/', ':', or '

By removing the : it was fixed.

This is a rebased version of GH-53.

Closes GH-53