Extend the rake task to support setting configuration options in the block

Adds support for setting any PuppetLint configuration options in the Rake task definition block

```
PuppetLint::RakeTask.new :lint do |config|
  config.pattern = 'modules'
  config.ignore_paths = ['modules/apt']
  config.disable_checks = ['documentation', '80chars']
end
```

/cc #305 @dalen