Add gke option

[arhamahmed]

Fixes #30

[arhamahmed]

This is GAE specific. Changing this to @config.config[:db_connection_options][:socket].split(":").pop is a better solution (extracts the Cloud SQL instance name from the required config.yml).

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[arhamahmed]

Oddly enough, exposing on port 80 with GKE made the gem server unaccessible. Some additional settings might be necessary in deployment.yaml.base.

[arhamahmed]

I signed it! (CLA)

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CLAs look good, thanks!

[arhamahmed]

@dazuma @hxiong388 I have finished adding the tests and doing some cleanup. Feel free to give the GKE implementation a whirl.

[tmaier]

Any update on this ❔