Updated the README and the install-prereqs-ubuntu.sh script to reflect
changes in the PX4 build steps and the PX$ & NuttX repository used to
build ardupilot.
* Added instructions on installing prerequisites in (Ubuntu) Linux.
* Added instructions on how to use vagrant for development.
* Minor copy-editing.
pch: rebased pullreq 183
* Converted to Markdown.
* Organization fix: Instructions on how to get the source come
first.
* Fixed old Google code URL to point to github instead.
* Grammar fixes.
* Added examples.
Andrew Tridgell
Craig Elder
Lucas De Marchi
The Gitter Badger
Randy Mackay
proficnc
wiseman
Kevin Hester
Andrew Tridgell
John Wiseman
Pat Hickey