Upload of 'pre'-transport packages to package manager

[Jako]

In addition to the commit c7984d7 the upload of 'pre'-transport packages should be possible:

'pre'-transport packages are zip-files that contain a complete build set that could be processed by MODX package builder i.e. a GitHub release file or GitHub repository file. For the Gallery Package this could be i.e. https://github.com/modxcms/Gallery/archive/production.zip and the files in https://github.com/modxcms/Gallery/releases

Those files could be directly retreived from the url into a special folder, they could be unzipped there and the build process could be triggered afterwards.

[opengeek]

That's a very cool idea @Jako

[Jako]

I have done something similar for Evo Package Manager (https://github.com/Jako/PackageManager) but I don't think that lot of the code is reusable.

A hopefully useful small hint: After retrieving the file from url, the zipped GitHub repository file contains one subfolder with _build, assets and core folders inside.

[Ibochkarev]

@Jako Can you make it happen?