fn: add header configuration to route calls (#371)

docs/swagger.yml

@@ -6,7 +6,7 @@ swagger: '2.0'
 info:
   title: IronFunctions
   description: The open source serverless platform.
-  version: "0.1.22"
+  version: "0.1.23"
 # the domain of the service
 host: "127.0.0.1:8080"
 # array of all schemes that your API supports
@@ -326,8 +326,12 @@ definitions:
             description: Name of Docker image to use in this route. You should include the image tag, which should be a version number, to be more accurate. Can be overridden on a per route basis with route.image.
             type: string
           headers:
-            type: string
+            type: object
             description: Map of http headers that will be sent with the response
+            additionalProperties:
+              type: array
+              items:
+                type: string
           memory:
             type: integer
             format: int64