add servo library to makefile
add servo library to makefile

juliahuang/TAMProxy-Firmware,juliahuang/TAMProxy-Firmware,gkanwar/TAMProxy-Firmware,skrub-wreckers/TAMProxy-Firmware,skrub-wreckers/TAMProxy-Firmware,gkanwar/TAMProxy-Firmware,mitchgu/TAMProxy-Firmware,mitchgu/TAMProxy-Firmware