Now a MX dns record includes the name parameter in the alias in order to...

When adding more than one MX entries in puppet and declarating the host param it fails because the generated alias for the dns::record is not unique, example:
```
  dns::record::mx {
    'mydomain-mx-10':
      zone       => 'mydomain.com',
      host       => '@',
      preference => 10,
      data       => 'ASPMX.L.GOOGLE.com';
    'mydomain-mx-20':
      zone       => 'mydomain.com',
      host       => '@',
      preference => 20,
      data       => 'ALT2.ASPMX.L.GOOGLE.COM';
```
In mx.pp the generated alias is (where the $host parameter is $name if not specified)
```
$alias = "${host},MX,${zone}"
```
So in both two previous entries the alias would be the same: "@,MX,mydomain.com"

I've modified the alias "hash" variable, and setting $name instead of $host, because we already know that $name is unique in the user generated puppet manifest file:
```
$alias = "${name},MX,${zone}"
```