Add the ability to respond only to certain events

[binford2k]

This adds a new webhook param, which allows you to define an event or
list of events to respond to as a single string or an array.

class {'r10k::webhook::config':
  enable_ssl        => true,
  protected         => true,
  repository_events => ['push','release'],
  notify            => Service['webhook'],
}

This required extending the webhook.yaml.erb to also expand and sort
array data types.

Yes, you could do the same by only configuring certain github events,
but this allows you to more easily do it in code on the master.

Limitations: currently supports only github events.

[binford2k]

Btw, I didn't muck with the spec tests, because they all fail on master for me.

[acidprime]

Try bundle exec rake spec <- offline converation

[acidprime]

This was failing for ruby 1.8.7 because of the way to_s used to work on arrays , fixed with 0b26d6d if your curious.