Swapped basename fallback function from os.tempnam to uuid

[mhocking2020]

This changeset removes the references to os.tempnam in some of the sample code used as a fallback when no filename is provided.
os.tempnam has been deprecated since Python 3.0 and was considered a symlink vulnerability prior to that:
https://docs.python.org/2.7/library/os.html
While the function is not actually used to generate temporary files in Nitro as intended, it still appears in SonarQube scans as a vulnerability.
Swapped to uuid to provide a non-deprecated function that provides unique file names while also not thrown as a vulnerability in SonarQube.

Test Steps:

• Install Nitro
• Add modules/python to Python path
• Remove os.path.basename(fileName) from the CLI calls to force it to hit the fallback
  • Line 71 in nitf_extract.py - Last variable
  • Line 73 in test_image.py - Last variable
  • This behavior is never encountered normally if you use the CLI as it will automatically use the input filename
• Run each and ensure you get the expected outputs
  • python nitf_extract.py {Path to Nitro}\modules\c++\nitf\unittests\sicd_50x50.nitf
    • Should produce 2 .out files that begin with a hex identifier
  • python test_image.py {Path to Nitro}\modules\c++\nitf\unittests\sicd_50x50.nitf
    • Should produce 2 .jpg files that begin with a hex identifier

[mhocking2020]

I can also see removing this fallback in favor of having it default to a generic "nitf_extract" / "nitf_image" base name as I do not really see why these had to be unique in the first place.

[adam-beauchamp]

LGTM