Description of problem:
When running targetcli via non-interactive shell, following traceback occurs.
    #  File "/usr/bin/targetcli", line 121, in <module>
    #   main()
    #  File "/usr/bin/targetcli", line 111, in main
    #    shell.run_interactive()
    #  File "/usr/lib/python2.7/site-packages/configshell_fb/shell.py", line 899, in run_interactive
    #    readline.set_completer(old_completer)
    # NameError: global name 'readline' is not defined

Version-Release number of selected component (if applicable):
targetcli-2.1.fb41-3.el7.noarch

How reproducible:
100%

Steps to Reproduce:
1. run targetcli < commands.txt with non-interactive shell
2.
3.

Actual results:
traceback

Expected results:
successful execution

Additional info:
Example of python code that will run an non-interactive shell:

def shell(cmd,complain_only=False):
    ''' runs a shell command and returns stdout '''
    log.debug("SHELL: %s" % cmd)
    p = subprocess.Popen(cmd,shell=True,stdout=subprocess.PIPE,stderr=subprocess.PIPE, bufsize=99999)
    stdout, stderr = p.communicate()
    p.wait()
    if p.returncode > 0:
        if complain_only:
            log.error("SHELL ERROR: %s" % stderr)
        else:
            raise Exception("Command failed(EC=%s): %s\nOutput: %s\nError-Output:%s" % (p.returncode, cmd, stdout, stderr))
    return stdout