'hp-uiscan -h' crashes with traceback

Hi,

I tried to run hp-uiscan on my Fedora before I package it, so I tried to run the script with '-h' to see what the tool does and what options it has and the tool crashed with traceback:

[user@localhost hplip]$ hp-uiscan -h

HP Linux Imaging and Printing System (ver. 3.18.12)
Scan Utility ver. 2.2

Copyright (c) 2001-15 HP Development Company, LP
This software comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to distribute it
under certain conditions. See COPYING file for more details.

Traceback (most recent call last):
  File "/usr/bin/hp-uiscan", line 31, in <module>
    opts, device_uri, printer_name, mode, ui_toolkit, lang=mod.parseStdOpts()
  File "/usr/share/hplip/base/module.py", line 430, in parseStdOpts
    self.usage(show_usage, error_msg)
  File "/usr/share/hplip/base/module.py", line 462, in usage
    utils.format_text(self.usage_data, show_usage, self.title, self.mod, self.version)
  File "/usr/share/hplip/base/utils.py", line 1664, in format_text
    for line in text_list:
TypeError: 'NoneType' object is not iterable

hp-uiscan does not have any definition of self.usage_data, so it gives traceback. I'm attaching the patch which creates basic help message and eliminates traceback. Would you mind adding it to the project?

Thank you in advance and have a nice day,

Zdenek
RHEL/Fedora hplip's maintainer