PM-732 added logic for users to specify finer grained linux versions
to stage the worker package for .  Users can specify in the site
catalog the osrelease and osversion attributes e.g.

<site  handle="exec-site" arch="x86_64" os="LINUX" osrelease="deb" osversion="7">

if a supported release version combination is not specified, then
planner throws a warning and defaults to the default combination for
the OS.
Merge remote-tracking branch 'origin/master'