Print help to stderr on error
    
    Whenever a command is used incorrectly, it should output
    an error message (and possibly additional help) to stderr.
    
    This patch adds a parameter to a bunch of places to allow
    selecting either stdout or stderr for help output, and makes
    badly called commands output to stderr only.
    
    Part of the effort for https://fedorahosted.org/freeipa/ticket/3060