Pull request #330 would add "ec2" ("ec2-user" after dash and whatever
follows has been stripped off) to GENERICUSERS for Amazon Linux. Now
that dashes-in-username handling has been fixed, that doesn't need to
be obscure and the full user name can be included instead.
I also added a commented out entry for PORTABLE_DEVICE_PATHS to the
default sysconf, then cloned that for Windows' sysconf.template.
Fixes#330
