Improve Windows packaging experience

Previously, when the DownloadCache was used on a Windows machine, it
could not read and write files properly.  This was due to it using the
default system encoding which differed from the expected UTF-8.  This
change updates the DownloadCache to always read and write files as
binary in order to get around the encoding issue.

Previously, when files were cached by the DownloadCache, the file
names were escaped to ensure that there were no forward slashes in
them.  On Windows, this escaping is not sufficient, as colons must be
escaped as well.  This change updates the escaping to cover this
additional case.

[#71925232][resolves #53]
Merge 71925232-windows-packaging-improvements to master

[Completes #71925232]
Merge remote-tracking branch 'upstream/master'