Reverse dependencies for rpi

Latest version of the following gems require rpi

Gem	Version	Date	Downloads
humble_rpi-plugin-doorlock +10.2 Thousand Downloads	`0.2.1` December 28, 2016	December 28, 2016	10.2 Thousand
humble_rpi-plugin-relay +3.76 Thousand Downloads	`0.1.0` September 26, 2015	September 26, 2015	3.76 Thousand
rpi_vibratingmotor +3.35 Thousand Downloads	`0.1.0` February 27, 2016	February 27, 2016	3.35 Thousand