Include source jar in dependencies

[ethauvin]

Implement support for including a package source jar in the dependencies, for example:

compileOnly 'pircbot:pircbot::sources:1.5.0'

which fails with:

*****
***** ERROR Error: Could not find artifact pircbot:pircbot:1.5.0:sources in Maven (http://repo1.maven.org/maven2/)
*****

Resolving does currently work:

``` $ k --resolve pircbot:pircbot::sources:1.5.0
              __ __           __              __   __
             / //_/  ____    / /_   ____ _   / /  / /_
            / ,<    / __ \  / __ \ / __ `/  / /  / __/
           / /| |  / /_/ / / /_/ // /_/ /  / /  / /_
          /_/ |_|  \____/ /_.___/ \__,_/  /_/   \__/  1.0.86

  Regular compilation time: 3558 ms
Downloaded artifact pircbot:pircbot:jar:sources:1.5.0 from Maven (http://repo1.maven.org/maven2/, default, releases+snapshots)
╔═════════════════════════════════════════════════════════════════════════════════════════╗
║                                 pircbot:pircbot:jar:sources:1.5.0                       ║
║                Maven (http://repo1.maven.org/maven2/, default, releases+snapshots)      ║
║           C:\Users\Cedric\.kobalt\cache\pircbot\pircbot\1.5.0\pircbot-1.5.0-sources.jar ║
╚═════════════════════════════════════════════════════════════════════════════════════════╝```