Insecure HTTP requests made by installer redirects

[milesmcc]

On line 41 of install/autocanary.nsi, the installer references an HTTP address: http://timestamp.globalsign.com/scripts/timstamp.dll.

Beyond the security risk an insecure request constitutes, the page itself redirects to https://www.globalsign.com/en/timestamp-service/, which does not seem like a timestamp. (It's a marketing page.) Perhaps the intended URL has changed?

Screenshot of the page that http://timestamp.globalsign.com/scripts/timstamp.dll redirects to (https://www.globalsign.com/en/timestamp-service/).

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This is potentially the underlying issue behind #30?

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I would submit a fix as a PR, but have no way of properly testing the changes because I am not running a Windows machine.

Thanks!