Fix #1889 - Align fat arrows

Fix [PUP-1889](https://tickets.puppetlabs.com/browse/PUP-1889).

Format resource's attributes according to the style guide, [section
9.2 "Arrow Alignment"](http://docs.puppetlabs.com/guides/style_guide#arrow-alignment).

## Current behaviour
I have a resource Exec['test']. If I indent the code (with for exemple `indent-region`), nothing happen.
```puppet
    exec { 'test':
      subscribe => File['/etc/test'],
      refreshonly => true, | ;; cursor is here
    }
```

Hit Tab, or select resource and call `indent-region`.
Nothing change.

## New behaviour
Same resource, attributes are formatted with Tab, C-m, C-j,
`indent-region`, etc.

```puppet
    exec { 'test':
      subscribe => File['/etc/test'],
      refreshonly => true, | ;; <- cursor is here
    }
```

Hit Tab. Attributes are formatted.

```puppet
    exec { 'test':
      subscribe   => File['/etc/test'],
      refreshonly => true, | ;; <- cursor is here
    }
```