replace roboto-fontface with fontsource

[goapunk]

see https://github.com/choffmeister/roboto-fontface-bower

[CarolingerSeilchenspringer]

@goapunk is this still relevant? if this is about the roboto font notice we got from client, then it is not relevant as long as we are not loading from external servers.

[goapunk]

no, it's just that the package we use is no longer maintained. Generally that's ok as it's just a font. So we don't need to touch this if we don't plan another sprint on tempelhof

[CarolingerSeilchenspringer]

@goapunk I will leave this open in case plans change but we don't have to touch this now.