Preferences panel with project status update

[sonec]

I did a lot of fiddling with the code last year that I completely forgot about. So instead of keeping it to myself, I think now is as good as any time to push it out there. It probably needs a bit of a polish.

I don't remember all the changes I made, though the commit log does tell a lot.

However, based on a browse of the code changes made, the following were done:

1. Added details on CPU usage preferences to the right hand panel
2. Provided a screen, accessible from the Activity menu, to update the computing preferences for the BOINC client
3. Made options on the Projects menu show the actually available actions that can be done with respect to resume/suspect project and allow/no new tasks