Delete previous builds about s3-plugin-webpack

[MikaAK]

That's outside the scope of this plugin

[ianks]

@MikaAK Can you elaborate on why it would be outside the scope of this plugin? Other tools (i.e. s3_website) handle this use case. From a user's POV, this feature would save a ton of hassle. s3-webpack-plugin has knowledge of all of the uploaded files, and thus it would be more robust to have s3-website-plugin to handle this.

[MikaAK]

This is more of an uploader but is turning into something more robust. Surprise and change is coming very soon just wait till then and maybe we can look back into it @ianks