title: How can I let sbt download the source of scala-library.jar?
body: <p>I know if I add withSources when I define one dependency, sbt can download that sources jar file automatically.
  For example,</p>
  
  <blockquote>
    <p>val specs = "org.scala-tools.testing" % "specs_2.8.1" % "1.6.6" % "test" withSources ()</p>
  </blockquote>
  
  <p>But for the scala-library.jar and scala-compiler.jar, I don't need define them explicitly, how can I get sbt download their sources for me? So, I don't need config it manually after generate idea project using sbt-idea-plugin.</p>