Add ginkgo e2e testing framework

[munnerz]

What this PR does / why we need it:

Adds a ginkgo based e2e testing framework, and updates the Elasticsearch e2e tests to be written with it.

fixes #32, fixes #156

Special notes for your reviewer:

Stacked on #241, #240 and #239

Release note:

NONE

[munnerz]

/test e2e

[munnerz]

/hold

[jetstack-ci-bot]

@munnerz PR needs rebase

[munnerz]

/hold cancel

[jetstack-ci-bot]

@munnerz PR needs rebase

[jetstack-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[munnerz]

/retest

[munnerz]

I got the following error when I tried running the tests on my dind cluster:

You've got --context=$HOSTNAME on your e2e test command, hence the error about missing context 😄

[wallrj]

You've got --context=$HOSTNAME on your e2e test command, hence the error about missing context

Sure, but I think I should be able to run make e2e-tests on my local cluster and it should just use the default context.

[jetstack-bot]

@munnerz: PR needs rebase.

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