Add *.KIDS, *.kids and *.txts to VA FOIA patch download instructions

Update instructions in 'Scripts/HowtoDownloadPatches.rst' to allow
*.KIDS, *.kids and *.txts to be downloaded from the VA FOIA site.  Disable in
'.gitattributes' whitespace these file extensions.

Update ConvertToExternalData script to check for *.KIDS and *.txts.

OSEHRA-Id: http://issues.osehra.org/browse/VAF-154
Change-Id: I6213071feb6622ab623da27f446eaf003f628c07
Merge "Add *.KIDS, *.kids and *.txts to VA FOIA patch download instructions"