Fix header misreporting to engine

[JakeDawkins]

Issue

When using the privateHeaders option in the constructor, not all expected headers were being reported to Engine.

This was caused because the loop iterating over the headers had a break where it should have had a continue, causing the loop to be cut short.

Note: This bug didn't cause any private headers to get reported, so no worries there 😄

TODO:

• Update CHANGELOG.md with your change (include reference to issue & this PR)
• Make sure all of the significant new logic is covered by tests
• Rebase your changes on master so that they can be merged easily
• Make sure all tests and linter rules pass

[evans]

@JakeDawkins Thank you for the PR! Not sure why we're getting package-lock differences. Are you running npm 6?

Also can you add this PR to the changelog?

[JakeDawkins]

@evans done! I wasn't on npm 6 🙈 There are still a couple diffs, all changing http urls to https. Not sure what's going on there, but significantly fewer than before.

[evans]

@JakeDawkins Thank you 🌮