title: Exclude base directory inside Gradle tar/zip artifacts
body: <p>The <a href="https://maven.apache.org/plugins/maven-assembly-plugin/assembly.html" rel="nofollow">maven assembly plugin</a> has an <code>includeBaseDirectory</code> option that (when set to false) avoids having a single top-level directory inside the tar/zip artifact with the same name as the artifact itself.</p>
  
  <p>I'd like to achieve the same result with Gradle, but I don't see how. I'm using  a configuration like this:</p>
  
  <pre><code>task distTar(type: Tar) {
      compression Compression.GZIP
      extension "tar.gz"
  }
  </code></pre>
  
  <p>I don't see any options for <a href="https://docs.gradle.org/current/dsl/org.gradle.api.tasks.bundling.Tar.html" rel="nofollow">the Tar task</a> that do what I want. How can I exclude the base directory in my archive with Gradle?</p>