Rails3 reports tabs

Fixes http://projects.puppetlabs.com/issues/18372 by refactoring the reports tabs a bit. The URL routes are changed so that they can be shared between reports and nodes cleanly:

```
OLD                    NEW
/reports/failed   /reports?status=failed
                  /node/123/reports?status=failed
```

Recall that feature was added recently in #112 / #152 so I'm not too worried about changing the URLs.