chore(package): update karma to version 1.6.0
chore(package): update karma to version 1.6.0

https://greenkeeper.io/
mseemann/angular2-mdl-ext,kononenko-a-m/angular2-mdl-ext,mseemann/angular2-mdl-ext,kononenko-a-m/angular2-mdl-ext,mseemann/angular2-mdl-ext,kononenko-a-m/angular2-mdl-ext,kononenko-a-m/angular2-mdl-ext,mseemann/angular2-mdl-ext