Adapt ARE Webserver start page

[klues]

Currently the startpage of the ARE webserver looks like this: http://prntscr.com/hm1tg6

The design of this startpage should be changend in order to fit with the design of WebACS.

[klues]

• design like WebACS Help
• left side links: link to webACS link to Help ** Demos -> REST-API, WebSocket, Further demos (online)

online demos to link: http://asterics.github.io/AsTeRICS/demos.html

[klues]

fixed with https://github.com/asterics/AsTeRICS/pull/211

startpage now looks like this: http://prntscr.com/hmh58p