Update Airbrake to play 2.1

I really wanted to use Airbrake with play 2.1 so this is the code that I ended up with after much toil. 
I am not a scala programmer and play 2.1 did change exceptions stuff so I am sure this could be done better but at least it works enough in 2.1 to use and be a starting point to make it work the right way.

Thanks for all your work in making this play module.