v0.1.4: Add a `headers` parameter to source (#5)

* Add the optional "headers" parameter

When specified, each header in the array will be added on to the request

Also only set the Authorization header when the "credentials" key is
provided

Authored-by: Matt Royal <mroyal@pivotal.io>

* Update wget to a version that follows redirects

Authored-by: Matt Royal <mroyal@pivotal.io>

* The output of "in" now includes the real version

Authored-by: Matt Royal <mroyal@pivotal.io>

* Add debug mode and ensure output isn't colorized

Also remove redundant "<" in calls to jq. jq takes a file as its second
argument

Authored-by: Matt Royal <mroyal@pivotal.io>

[#170560744] Automatically trigger fan-out job in Concourse when all train stories for the product+version have passed canary

* Make jq filter optional