Allow condor_ssh_to_job to see the job when USE_PID_NAMESPACES is true #3872

This is the quick fix for stable.  Perhaps in devel we should move the
startd into the pid namespace.
Remove accidentally added file
Document #3872
fix for #3902, condor_submit - doesn't read submit from stdin.
===VersionHistory:Pending===
Merge branch 'V8_0-branch' into V8_1_1-branch