Updated USB networking drivers

See http://beagleboard.org/Getting+Started#step2 for the updated drivers

Mac users: The HoRNDIS driver from Joshua Wise has been updated to
release 5. I've heard reports on Twitter than this fixes Internet
Connection Sharing issues.

Windows users: The drivers have been signed now by sysco.ch, so
installation should be simpler. This does however mean that a 3rd
party touched the binaries.

Relavent patches:
* https://github.com/beagleboard/beaglebone-getting-started/commit/b5019710c543ed9ffcd84bd7d1ea71c0d6372cd9
* https://github.com/beagleboard/beaglebone-getting-started/commit/6e2240697a83697c84eb9f9f10a6fd976f5c3ce8