This is a general tidyup to detach this fork better from Gordon, who was (and perhaps still is) completely inundated with WiringPi-related support questions.

This changeset includes a number of tweaks which should reduce support burden on Gordon. I believe they are essential if we plan to release a new debian package.

They should - hopefully - not reduce or make ambiguous the origins of this code while achieving the above.

* Remove Gordon's email address from all source files to avoid support queries finding their way to him
* Update wiringPi URLs to the GitHub repository to try and keep bugs/issues within the fork
* Bump version to 2.70 ready for a debian package release
* Update debian package maintainer info, add bugs & homepage URLs to this repository

Moved the extensions into wiringPi from gpio and made it more general purpose
more so that RTB and anything else can dymanically add devices
into wiringPi.
Changes to GPIO to updates for the SPI and I2C module loads
Added gpio unload for SPI and I2C.

Added a new way to setup SPI - by passing the mode in.

Support for the new Pi2 thing too