List done tasks in visualizer

List done tasks in visualizer as well as upstream failed and failed.

Show "Dependency graph" button for done tasks

Show "Dependency graph" not "Show error trace" button for done tasks in
task list.

![done_tasks](https://f.cloud.github.com/assets/2633943/746904/4c8f43c0-e43e-11e2-8274-645b13118c58.png)