#4 Task/Job stats display

[Keith Flanagan]

Several GUI ideas. The data required for these is already stored inside the JobServer database:

* Graph / table showing the amount of time a selected job or collection of jobs spends in each of the possible job states.
* Graph / table showing the amount of time the system as a whole spends in each state.
* The same, but for currently active jobs
* A timeline display for a specified job, showing when it changed state, and how long it remained in those states.