zaml: don't sort object attributes for output

Sorting YAML attributes makes for marginally nicer human-friendly YAML output,
but ends up costing a non-trivial amount of computation to determine the
ordering of objects.

We can skip that with pretty much no adverse effects.

Signed-off-by: Daniel Pittman <daniel@puppetlabs.com>

Conflicts:
lib/puppet/simple_graph.rb
lib/puppet/transaction/event.rb
lib/puppet/transaction/report.rb
spec/unit/util/log_spec.rb

Signed-off-by: Daniel Pittman <daniel@puppetlabs.com>