[nginx] pass non-SNI TLS hello to default backend, Fixes #693

[donaldguy]

tested with image pushed to quay.io/donaldguy/nginx-ingress-controller:no-sni

Just verified that sites still load and that openssl s_client now works
w/ AND w/o a servername.

Fixes #693

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[k8s-reviewable]

This change is 

[coveralls]

Coverage decreased (-0.03%) to 47.124% when pulling 2d1b6dc on donaldguy:nginx-no-sni into 4601775 on kubernetes:master.

[aledbf]

@donaldguy please sign the CLA

[ghost]

Confirmed that this fixes the problem. Waiting on @donaldguy to sign CLA. Patch is needed for this to work correctly.

[donaldguy]

Should be good now. I was waiting on cofounder of Tulip to sign CCLA

[aledbf]

/lgtm

[aledbf]

@donaldguy thanks!