Add storage sample environments

Add storage sample environments

Starts converting storage-related sample environments to the tool,
and adds a few new ones for demonstration purposes.

This has required the addition of a new category of parameter
overrides in the tool.  There are some parameters that are part of
the public API of roles that should not normally be included in a
sample environment for that role.  Examples are EndpointMap and
ServiceNetMap.  Those are both passed into most (all?) roles, but
their template defaults are not useful (both default to {}).
Unless we are explicitly creating a sample environment that
overrides those defaults we don't want them included.

Parameters such as RoleName and RoleParameters are similar.  We
can't change them because they are part of the composable roles
interface and that would break any existing custom roles, but we
don't really want them included normally either.  It's possible
these could be made completely private, but there have been some
very preliminary discussions about generating role samples that
might actually want to set them.

In order to avoid issues with editing the unit test file in editors
that strip trailing whitespace, the minor formatting bug where
params like EndpointMap had a trailing space after the name has
also been fixed.

Change-Id: If11f30c734bfbc17d463a9890c736d7477186fb9