chore(package): update coveralls to version 2.13.1
chore(package): update coveralls to version 2.13.1

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