Optional parameters to add the source tag in the composer package json

[fghamsary]

With the PUT command via HTTP it is possible to send the zip file only, and the "dist" tag is generated automatically.
But here is a "source" tag which can be added as well, which should be supported via the "PUT" command in my opinion.
This will permit people to use the meta data via PUT command as a multi-part value to send the URL, type and the reference for the source code as well.
This will add the "source" tag automatically to the attributes of the package and will provide these fields via packages.json endpoint which is great for knowing the version corresponding in the composer repository is which version in the source control such as git with the reference tag.
I've implemented this feature for our own usage, but it might be a good idea to integrate it for other people as well.

I'll add a Pull Request for this feature shortly.
Thanks in advance.