Reverse dependencies for wiringpi2

Latest version of the following gems require wiringpi2

Gem	Version	Date	Downloads
frankenpins +7.38 Thousand Downloads	`0.3.0` November 29, 2013	November 29, 2013	7.38 Thousand
i2c-alpha_display +7.15 Thousand Downloads	`0.5.1` January 05, 2017	January 05, 2017	7.15 Thousand
overspeeding +3.3 Thousand Downloads	`1.0.0` January 28, 2016	January 28, 2016	3.3 Thousand