2-28-03 Node table column obsolete

I've obsoleted the "os" column in the node table. Instead of putting stuff here that was delimited with a colon (i.e. "linux:redhat:8.0") use the attributes column and insert "os_type=linux,os_distribution=redhat,os_version=8.0" instead.

The documentation (DTF.sxw in the docs directory of the dtframework module) contains detail on the column and recommended attribute names (the sames ones in the sample above).