OptionParser Python 2.4 compat fix

Python 2.4 OptionParser can't display an epilog message so tack it onto
the end of the usage.  This does not look as nice, but still gets the
point across.  (SOFTWARE-1669)
Merge remote-tracking branch 'bbockelm/master'
Add a user-friendly error message when reconfig fails in condor_ce_config_generator (SOFTWARE-1705)

This also fixes a Python 2.4 incompatibility (since
subprocess.CalledProcessError did not exist in Py2.4)
Merge pull request #57 from matyasselmeci/master

OptionParser Python 2.4 compat fix