Raspi 2: Move system root to usb-SSD

[sihui]

works great:

Booting Raspberry Pi 3 (RPi3) from USB mass storage without sd card

Update December 2017: This tutorial is outdated. With newer version of Raspbian you can install an USB SSD the same way as a sd card. A lot of openHAB users are concerned about the reliability of sd cards. Under certain circumstances while using persistence services and with a lot of read/write cycles through openHAB and system logging they tend to worn out. For the RPi3 there is a new USB mass storage boot mode which allows to boot the operating system from a harddisk, preferable an SSD har…