Add 'Remove' button also for queued jobs

This simply adds the "Remove" button also for queued jobs. It still doesn't cover all the cases (i.e. when a job fails with the ```ERROR Unknow key oq-platform in PLATFORM_DATABASES; you forgot to set local_settings.py``` exception).

See this example
![screen shot 2014-09-05 at 17 46 23](https://cloud.githubusercontent.com/assets/1818657/4167502/fa55ebd6-3513-11e4-9f1e-556f30be4082.png)