bug: fix traceback in roundup-admin init with bad config values initialize accepts setting values for config.ini file settings. If they are not valid, you got a python traceback. ConfigurationError exceptions are now trapped. The admin.py's usageError_feedback method is used to inform the user. Also the feedback message now starts with a newline making it easier to read by separating it from command that caused the issue.

try:
    from html import escape as html_escape_  # python 3

    def html_escape(string, quote=False):
        # html_escape under python 3 sets quote to true by default
        # make it python 2 compatible
        return html_escape_(string, quote=quote)
except ImportError:
    # python 2 fallback
    from cgi import escape as html_escape  # noqa: F401