web-landing-modemrouter: new landing package for cable modem routers …

web-landing-modemrouter: new landing package for cable modem routers (#24)

* [SW-2179] update the styling for the web landing page
* [SW-2179] update link and add some responsive design tweaks
* [SW-2179] update makefile
* [SW-2179] fix margin

SW-604
SW-2179