Preparations for REST-based cat feeder

* Own Arduino_Rest_Server (bugfix stream.h -> Stream.h include)
* Cleaned up feedservo.h into its own namespace
* Added ntp.h (NTP time sync)
* Ethernet initialization with IP 192.168.2.2
  TODO: make sure dns server is running on router at 192.168.2.1
* REST menu containing:
   feed_now [0,1] r/w
   skip_feed [0,1] r/w
   servo_neutral [0..180] r/w
   feed_in [1..86400] r/w