Update karma version

> [INFO] npm ERR! peerinvalid The package karma does not satisfy its siblings' peerDependencies requirements!
> [INFO] npm ERR! peerinvalid Peer grunt-karma@0.7.3 wants karma@~0.12.0
> [INFO] npm ERR! peerinvalid Peer karma-jasmine@0.1.5 wants karma@>=0.9
> [INFO] npm ERR! peerinvalid Peer karma-phantomjs-launcher@0.1.4 wants karma@>=0.9
Updating karma version to ~0.12.0 fixes this problem