Gittrac #3532:  A fair amount (but not all) of values are correctly
written to the metrics file; no provision to actually report to the
server yet, though.
Gittrac #3532:  Parsing of braindump.txt file now works, and the
values from that file are reported in the metrics; a little bit of
cleanup of other stuff.
Gittrac #3532:  Added dagman_id and parent_dagman_id values to the
metrics file.
Gittrac #3532:  Cleaned up the metrics file output as per feedback
from nwp.
Add the dagman_metrics_reporter #3532

This franks, but I need to find out from Kent and the design document
which environment variables will be used and also what is supposed to
happen with the DAGMan status
Using the wrong curl options so fix it #3532
Handle environment variables and make sure we die after 100 seconds #3532
Actually fork the dagman_metrics_reporter #3532
Indicate which server succeeded or failed #3532
Fix up formatting and move code out of inner loop #3532
Put the metrics reporter in libexec, not bin #3532
Report all errors from libcurl #3532
Want to include header for sleep #3532

Do not build the metrics reporter unless we have libcurl
Gittrac #3532:  We now only try to read the braindump.txt file if
metrics reporting is enabled; failure to read braindump.txt is
now strictness level 2, not 1; a few other cleanups.
Gittrac #3532:  We now report metrics if the DAG fails; added first
metrics test (checking not yet fully in place, but okay for manual
testing).
Gittrac #3532:  Fixed syntax error in metrics output (trailing comma
on last item); temporary fixes to get condor_dagman_metrics_reporter
to run for testing; DAGMan now passes the output file name instead of
the DAG file name to condor_dagman_metrics_reporter (so we can
put the reporter's output file into the dagman.out file); added
copyright to condor_dagman_metrics_reporter.cpp.
Gittrac #3532:  DAGMan now tells condor_dagman_metrics_reporter
whether to sleep, rather than passing the DAG status value and
having the reporter figure that out; we now param for LIBEXEC
to get the path to condor_dagman_metrics_reporter.
Gittrac #3532:  client and version in the metrics now refer to
DAGMan; planner and planner_version are from the braindump.txt
file.
Gittrac #3532:  Instead of having condor_dagman_metrics_reporter open
the output file, we open the output file in DAGMan itself and pass it
as stdout and stderr to Create_Process() -- that way, errors from
libcurl, for example, show up in the output file.
Gittrac #3532:  Now using the UtcTime class to avoid problems building
on Windows.