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:
    # Python 2.
    my_input = raw_input
except NameError:
    # Python 3+.
    my_input = input