Support for CloudFront invalidation with given path.

[skydan]

Default "*" value for paths is better than nothing, but it'd be nice to have a way to manage it.

[m00k]

I also need this feature. It would be great if the plugin would support something like

cloudfront:
  distribution: 9c5785d3ece6a9cdefa4
  invalidation_paths:
    - "index.html"
    - "somePath/**/*.js"

resulting in invalidation of index.html and all javascript files under the path somePath (while not touching other files).

[tboerger]

Feel free to provide a pr that extends https://github.com/drone-plugins/drone-s3-sync/blob/master/plugin.go#L146 :)