chore(package): update webpack-dev-server to version 2.4.3
chore(package): update webpack-dev-server to version 2.4.3

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