Uninstaller should not clean up VirtualStore folder for current user.

The uninstaller was deleting any VirtualStore items that may have been created
by Zotero. This is not necessary because Zotero's executable contains a
manifest which prevents Windows from using file virtualization.
Merge pull request #17 from mikesteele81/windows-file-virtualization-cleanup

Uninstaller should not clean up VirtualStore folder for current user.