cjohansen/Sinon.JS — pull request #548 by elliottsj (2014-08-16 03:36:00+00:00)
Title: Fix #547 by case-insensitively finding the header name

Fixes #547

- Added a unit test to ensure an existing `"content-type"` header prevents a `"Content-Type"` header from being inserted.
- Added a helper function `getHeader` used by both the `send` and `getResponseHeader` functions to find the name of a header, ignoring case.