title: Cobertura task is not getting included as part of gradle build
body: <p>I am doing a build using gradle. When I do a "gradle clean build" it executes all my test cases and build succeeds. When I do a gradle clean cobertura it generates my cobertura report. I want to integrate cobertura reports as part of gradle build. I tried in the below option in build.gradle, but it gives me an error.</p>
  
  <pre><code>build{
  
   dependsOn cobertura
  
  }
  </code></pre>
  
  <p>Error that i got. Any thoughts on this?</p>
  
  <pre><code>Could not determine the dependencies of task ':build'.
  &gt; Cannot convert net.saliman.gradle.plugin.cobertura.CoberturaExtension_Decorated@528e5e38 to a task.
  The following types/formats are supported:
  - A String or CharSequence task name or path
  - A Task instance
  - A Buildable instance
  - A TaskDependency instance
  - A Closure instance that returns any of the above types
  - A Callable instance that returns any of the above types
  - An Iterable, Collection, Map or array instance that contains any of the above types
  </code></pre>