Avoid removing records with different type on create

Create method on record LWRP doesn't match with the type of the record, so if any record with the same `name` will be deleted.

Given:

```
    A 1.1.1.1
    MX wadus
    NS 1.1.1.1
    CNAME wadus
```

and this lwrp call:

```ruby
dnsimple_record '' do
  type 'CNAME'
  content 'newvalue'
  domain 'example.com'
  username 'user@email.com'
  password 'my123password'
end
```

This will raise on deleting the first record obtained from the API.

Closes #9