Add ability to specify nginx access log format

[rvadim]

Hi, This PR add ability for customizing nginx access log format through router deployment annotations.

We need this ability to migrate from deis 1.x.

[deis-admin]

Thanks for the contribution! Please ensure your commits follow our style guide. This code will be tested once a Deis maintainer reviews it.

[deis-bot]

@mboersma, @helgi and @krancour are potential reviewers of this pull request based on my analysis of git blame information. Thanks @rvadim!

[codecov-io]

Current coverage is 55.23% (diff: 100%)

Merging #290 into master will increase coverage by 0.11%

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Powered by Codecov. Last update 563d731...2f287d0

[mboersma]

Jenkins, add to whitelist.

[krancour]

I'd want @jchauncey to have final say on this. This might affect the metrics that are collected from the router.

[jchauncey]

Yes if you change the router log format in any way you will definitely jack up the router metrics we collect. So while I'm not opposed to this we should have a warning if you change it.

[rvadim]

So, any tasks for me here? Need to add warning to log?

[krancour]

@rvadim I think you'd need to add a warning to the documentation for this feature.

[rvadim]

Done, but get CI error in infrastructure.

[bacongobbler]

thanks @rvadim!