Add the original http request method to the auth request

[chrisblu]

What this PR does / why we need it:
Added the original http request method to the auth request. This is for example useful for granting access depending on reads/writes.

Access the original http request method in auth subrequests

[k8s-reviewable]

This change is 

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[coveralls]

Coverage remained the same at 37.096% when pulling 2dfaaa7 on chrisblu:master into 9cec069 on kubernetes:master.

[aledbf]

/lgtm

[aledbf]

@chrisblu thanks!