Due to the shortened format of the Denver Summit we
need to make sure that the trainees do more work before the
summit than we normally have to. This adds steps to the
page to get the trainees to do more setup before the Summit.
It also adds a number of warnings to the trainees about the
importance of preparing.
Finally, this includes a link to the new VM image for
the Denver Summit.
Change-Id: I3ad612450b24d15d1d9d308f22c49c22f742d9d6