R1:a2a4f4b3da92

Fix validation of Harbormaster HTTP methods

Summary: Precedence here was mucked up.

Test Plan: Plan with no explicit "method" now defaults to POST correctly.

Reviewers: dctrwatson, btrahan

Reviewed By: btrahan

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D8559