Update the readme

Many things in the readme were out of date, old, overly documented, or
downright wrong.  This commit attempts to update all the things that
need updated.  If any of them are controversial, I'm happy to break down
this patch more, but I suspect most of these should be reasonably
correct.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: Icbe4be024d71aa596fccb53b91c6661964238b2c