Major Cleanup

Cleaned up a lot of the WiringPi references, etc.

Updates to match actual interfaces, mainly raw SoC Pins, notes on power, DPI, JTAG.

Need to update the rest of the interfaces next and also tackle Expansion hats... might "remove" most/all and add one by one as we test? @jkridner Opinion here?

@lorforlinux Will need your help to please add a page on docs.beagleboard.org for each of the interfaces so I can link to it from the top level pages. It's ok if they're blank... things like SPI, I2C, 1-Wire etc.