Description of problem:
satpassd does not accept punctuation characters in username.

For example:
user_a is not treated as a valid username when changing password with satpasswd even though username is accepted within spacewalk.

Version-Release number of selected component (if applicable):
spacewalk-base-2.2.33-1.el6.noarch

How reproducible:
satpasswd user_a

Steps to Reproduce:
1. Create user_a in spacewalk
2. In CLI on server, run "satpasswd user_a"
3.

Actual results:
[root]# satpasswd user_a
Usage: satpasswd [OPTIONS] user

Options:
        -h, --help      Print this help message.
        -s, --stdin     Read the password from standard input.


Expected results:
Should prompt for password.

Additional info:

This is the cause of the problem:
    if not userIn.isalnum():

It incorrect only permits alphanumeric.