Reverse dependencies for wiringpi2

Latest version of the following gems require wiringpi2

Gem	Version	Date	Downloads
frankenpins +7.42 Thousand Downloads	`0.3.0` November 29, 2013	November 29, 2013	7.42 Thousand
i2c-alpha_display +7.17 Thousand Downloads	`0.5.1` January 05, 2017	January 05, 2017	7.17 Thousand
overspeeding +3.32 Thousand Downloads	`1.0.0` January 28, 2016	January 28, 2016	3.32 Thousand