teach Remove-BinFile to remove shim .exes

Additionally, print messages about nonexistent batch redirects only in
debug mode. Remove-BinFile does not know which method was used to create
the redirects and the messages are false positives if shimgen was used.
Besides, those messages are useless to the end user anyway.
Merge pull request #480 from jberezanski/remove-shims-upon-uninstall-stable

Improved Remove-BinFile to remove shim .exes when uninstalling a package