Update Lint to default to Puppet Approved criteria

So I don't believe that you need to clear the `:lint` task here, as this would be the only `:lint` defined at this point in time.

The reason I had to do it in my module `Rakefile` was because I was overriding this task.  Once the `ignore_paths` have been set, they cannot be changed.  As mentioned, only the first `:lint` task will be the one run by Rake, so if you wish to change `ignore_paths`, then you have to ensure that there is one task.

For reference, my module uses this code:

```ruby
# necessary to ensure default :lint doesn't exist, else ignore_paths won't work
Rake::Task[:lint].clear

PuppetLint.configuration.relative = true
PuppetLint.configuration.disable_class_inherits_from_params_class
PuppetLint::RakeTask.new :lint do |config|
  config.ignore_paths = ['contrib/**/*.pp', 'tests/**/*.pp', 'spec/**/*.pp', 'pkg/**/*.pp']
end
```