Added bugfix about help on argparse commands

Author: kmvanbrunt

CHANGELOG.md

@@ -2,6 +2,7 @@
 * Bug Fixes
     * Fixed bug where ``get_all_commands`` could return non-callable attributes
     * Fixed bug where **alias** command was dropping quotes around arguments
+    * Fixed bug where running help on argparse commands didn't work if they didn't support -h
 * Enhancements
     * Added ``exit_code`` attribute of ``cmd2.Cmd`` class
         * Enables applications to return a non-zero exit code when exiting from ``cmdloop``