Long custom app name fails to package on Windows

[sjh26]

• Long names generate too long paths in packaging directory on windows.
• The default name is long enough to trigger this with a non release (dated) package name.
• Perhaps we should put in a cmake warning/error if the name is too long?
• See: http://slicer.cdash.org/viewBuildError.php?buildid=1821163

Error example:

File: Descending to: "D:/D/P/SC-0-build/Slicer-build/_CPack_Packages/win-amd64/NSIS/SlicerCustomAppTemplate-0.1.0-0000-00-00-win-amd64\lib\SlicerCustomAppTemplate-4.11\qt-scripted-modules\SegmentEditorEffects\SegmentEditorEffects\__pycache__\"

File: failed opening file "D:/D/P/SC-0-build/Slicer-build/_CPack_Packages/win-amd64/NSIS/SlicerCustomAppTemplate-0.1.0-0000-00-00-win-amd64\lib\SlicerCustomAppTemplate-4.11\qt-scripted-modules\SegmentEditorEffects\SegmentEditorEffects\__pycache__\AbstractScriptedSegmentEditorAutoCompleteEffect.cpython-36.pyc"

Error in script "D:/D/P/SC-0-build/Slicer-build/_CPack_Packages/win-amd64/NSIS/project.nsi" on line 639 -- aborting creation process