Fixed my Gwibber

Since I got back from UDS, Gwibber has been broken on my main machine. I knew it was something to do with WebKit, but I just didn't get around to looking any further into it until today. ...and I didn't have to look far - there's a question and bug for exactly this problem, with a simple 2-step fix:

1. Make sure you don't have the WebKit Team PPA enabled
2. Make sure you downgrade the libwebkit package is version 1.0.1-2 (the default version in 8.10), not 1.0.1-4 (the WebKit Team version)

That's it - restart Gwibber, and it should be working again.