Allow pasting in preference dialog

[daften]

Now pasting doesn't work (on Mac OS X), this would be handy for the access token and potentially also for the URL.
There also isn't a save button, but also nothing that shows the access token is actually valid, so a type can be very annoying.

[kriskbx]

Thanks for pointing this out. It should be fixed in v0.3.7 which is beeing built right now. :)