Update karma.conf to work with karma 0.10.x

In the course of debugging an issue I added some tests to 
angular-pouchdb. The tests didn't turn out to be useful, but I had
to update karma.conf.js to work with the newest karma, so I figured
I'd share that.

I also ended up reading all of the angular-pouchdb code carefully
and now understand promises better, so not a total time waste.
Thanks for the excellent glue @wspringer.