Abstracting Register and Gpio.

--HG--
rename : i2c/src/main/scala/org/podval/iot/i2c/ByteRegister.scala => i2c/src/main/scala/org/podval/iot/i2c/ByteRegisterI2c.scala
rename : i2c/src/main/scala/org/podval/iot/i2c/WordRegister.scala => i2c/src/main/scala/org/podval/iot/i2c/WordRegisterI2c.scala