Uses the BuildStructureChanged event to extract available projects

@Warry, can you please take a look at this PR before it's getting merged.
The project drop-down list doesn't look good in Chrome on OSX (haven't tried FF) with this update.
Leaving the build page and coming back makes the browser render the list okay so it seems to be some UI trick that's needed.

Can you try running it with hello-akka as a project (that's what I did and it works for me).
Also, add some logging to see that you get any projects at all.