Fixing web proxy dealing with protocols

[jdoubleu]

See #57 and mattermost/mattermost#3944

Added workarounds to both nginx configs (ssl and no ssl) to grab the correct protocol and pass it in the X-Forwared-Proto header.

If this web proxy receives a connection which already has X-Forwared-Proto set it will use this, otherwise it will sue default $scheme variable.

[monty241]

@jdoubleu Hi John, would it be helpful when I would change our generated nginx configuration by hand with the changes in the files and checked whether it solves our mattermost/GitLab integration issues?
After that I can re-generate them so no lasting harm done in our production environment.

[jdoubleu]

I can confirm this works.

Tested it in my environment (described here: mattermost/mattermost#3944 (comment)) using the new nginx config file.

[eungjun-yi]

Thanks @jdoubleu for the pull request!

Per the CONTRIBUTING.md file displayed when you created this pull request, we need to add you to the list of approved contributors for the Mattermost project.

Please help complete the Mattermost contribution license agreement?

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Please let us know if you have any questions.

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[eungjun-yi]

Sorry for late response!

[eungjun-yi]

@jdoubleu Could you please help the complete the license agreement?

[jdoubleu]

@npcode sorry for the delay. Didn't get notified about changes here, for some reason.

I filled out the license agreement.
Is there anything else I have to consider? E.g. changing the title to the Jira Ticket ID?

[eungjun-yi]

@jdoubleu That's all. Thanks!