Admin User-IP locator

[gnunicorn]

Implements the step 1-3 of the Admin User-IP-Locator spec as discussed here:

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Details:

• when an IP given, with a click on the new "lookup" button the Admin can trigger an IP-Reverse look up
• uses ipinfo.io directly through jsonp (avoids round-trips)
• shows hostname, location and all known details (if found)
• automatically links long-lat to a google-maps link opening in a new window/tab
• looks up other users also using that IP and shows them under

Notes:

• misses copy-edit/translations (and therefore will probably fail the travis build)
• the "No Hostname" I receive back from ipinfo as a value

[discoursebot]

You've signed the CLA, ligthyear. Thank you! This pull request is ready for review.

[coding-horror]

Looks amazing will be a huge help!

[SamSaffron]

Looks good to me, but please let's include English strings, @coding-horror can improve copy later on.

[coding-horror]

You can just include hello world strings, happy to edit right after merge

[gnunicorn]

@coding-horror , @SamSaffron . Added string stubs. Rebased for prettier history.

[SamSaffron]

@ligthyear not merging cleanly anymore, can you fix

[coding-horror]

@ligthyear can you give this some adjustment? Then we can merge and I can contribute copy. Anxious to see this shipping!

[gnunicorn]

rebased. Applies cleanly again. Ready to be shipped.

[SamSaffron]

Thanks!