Reverse dependencies for rpi

Latest version of the following gems require rpi

Gem	Version	Date	Downloads
humble_rpi-plugin-doorlock +10.5 Thousand Downloads	`0.2.1` December 28, 2016	December 28, 2016	10.5 Thousand
humble_rpi-plugin-relay +3.83 Thousand Downloads	`0.1.0` September 26, 2015	September 26, 2015	3.83 Thousand
rpi_vibratingmotor +3.39 Thousand Downloads	`0.1.0` February 27, 2016	February 27, 2016	3.39 Thousand