Improving expressiveness of parser --help

The patch adds a one-line description as it would appear behind
the name of a yet non-existing man page. This is meant to eventually
help auto-creating it.

Author: smoe

cwltool/cwltest.py

@@ -131,7 +131,7 @@ def run_test(args, i, t):
 
 
 def main():
-    parser = argparse.ArgumentParser()
+    parser = argparse.ArgumentParser(description='Compliance tests for cwltool')
     parser.add_argument("--test", type=str, help="YAML file describing test cases", required=True)
     parser.add_argument("--basedir", type=str, help="Basedir to use for tests", default=".")
     parser.add_argument("-n", type=int, default=None, help="Run a specific test")

cwltool/main.py

@@ -29,7 +29,7 @@
 _logger.setLevel(logging.INFO)
 
 def arg_parser():
-    parser = argparse.ArgumentParser()
+    parser = argparse.ArgumentParser(description='Reference executor for Common Workflow Language')
     parser.add_argument("--conformance-test", action="store_true")
     parser.add_argument("--basedir", type=str)
     parser.add_argument("--outdir", type=str, default=os.path.abspath('.'),