new solaris sample
test prtdiag parsing
more sensible constants
don't memoize getPrtconfInfos()

It is used only once
fix key name
add new /etc/release parsing function

see: #2736
use shared getReleaseInfo() function
cleanup HARDWARE and OPERATINGSYSTEM sections

We don't care about SunOS version, but we care about Solaris minor
version (aka "service pack").

closes: #2736
first attempt to detect docker container

closes: #2731