Add possibility to make a distribution by Cargo

[iddm]

Both Maven and Gradle have an ability to make a local distribution package, for example, some .zip archive which will contain some data you want. You may not want to publish your rust project on crates.io but, for example, you want to have your own project's web-site which has "downloads" section instead. With maven and gradle this would be possible.

So, I suggest cargo to have options to:

1. Build a distribution package (zip, tar, gz, other formats)
2. Count hashsumm (md5, sha256) automatically for the file from step 1.

What do you guys think here?

[jonas-schievink]

FYI There's already cargo package, might want to check it out to see how far it gets you

[iddm]

Afaik this does something I can't control. My proposal' intentions are to provide a way of controlling what and how you want to package.

[est31]

see also rust-lang/cargo#557