Simplify initial setup

[dernasherbrezon]

• If raspberrypi is not connected to the wi-fi, then
• start wi-fi access point
  ** SSID "r2cloud"
  ** password "r2cloud"
  ** all requests should be redirected to default web site
• default web site should display page with the list of wi-fi networks
• it should be possible to select wi-fi network and save password for that network
• setup token
• access point should be switched off and connected to the selected wi-fi network
• normal r2cloud setup should be available

This will simplify initial setup:

• no cable required for wi-fi-based networks
• no monitor/keyboard required
• easy to configure wi-fi connection

Cons:

• older raspberrypi (without wi-fi) won't support this