The Content-Type header should be more accurate.

We're not sending back HTML, we're sending back specific codes for
a specific printer. The content type should therefore indicate that,
and match the type in the `HTTP_ACCEPT` header.

Closes #42

lib/printer/backend_server/polling.rb

@@ -7,6 +7,7 @@ class Printer::BackendServer::Polling < Printer::BackendServer::Base
     printer = Printer::RemotePrinter.find(params["printer_id"])
     printer.update(remote_printer_params(params))
     Printer::PrinterIPLookup.update(printer, request.ip)
+    headers "Content-Type" => env["HTTP_ACCEPT"]
     printer.data_to_print
   end
 

test/backend_server/polling_test.rb

@@ -29,6 +29,14 @@ def app
       get "/printer/1"
       last_response.body.must_equal "data"
     end
+
+    it "responds with a content type that matches the printer type" do
+      printer = Printer::RemotePrinter.new("1")
+      Printer::RemotePrinter.stubs(:find).with("1").returns(printer)
+      printer.stubs(:data_to_print).returns("data")
+      get "/printer/1", {}, {"HTTP_ACCEPT" => "application/vnd.freerange.printer.printer-type"}
+      last_response.headers["Content-Type"].must_equal "application/vnd.freerange.printer.printer-type"
+    end
   end
 
   describe "updating printer information" do