The current testing always starts from scratch.
However, in practice we do not rebuild all our machines from scratch
on every change, but instead usually incrementally upgrade them.

Run the tests both from scratch, which is used whenever we stand up
a new builder, and as an upgrade from the previous configuration, which
is the more common case.

Additionally, the Salt installation and Salt grains.items and
state.show_highstate commands produce output that is useful for
debugging, but is normally not necessary to view.
Add special markers to the build log that fold these sections on Travis.
This is especially useful with the longer build logs.