Creating and deploying a Workflow Code Activity (SharePoint 2013, Visual Studio 2012)

I need to deploy and DEBUG a SharePoint 2013 workflow in Visual Studio 2012 containing a code activity, to a SharePoint 2013 server. Information on how to do this is a bit scarce, but information on how to successfully debug it does not seem to be available anywhere. Can someone list down the steps I need to take to do this? I can't get visual studio to attach to a workflow when it contains a code activity. These are the steps I've taken so far:

1. Create SharePoint empty project
2. Add a workflow to the SharePoint project
3. Add an Activity library to the solution
4. Create a code Activity in the Activity Library
5. Open the workflow in the visual studio designer and drag the code activity to the sequence.
6. Add a breakpoint to the first step in the workflow
7. Followed this tutorial here: http://blogs.technet.com/b/sharepointdevelopersupport/archive/2013/08/28/how-to-develop-a-workflow-code-activity-in-sharepoint-2013.aspx and created an AllowedTypes.xaml, copied the DLL and AllowedTypes.xaml to %ProgramFiles%\Workflow Manager\1.0\Workflow\Artifactsand %ProgramFiles%\Workflow Manager\1.0\Workflow\WFWebRoot\bin, restarted Workflow Manager backend service, installed the DLL in GAC (do I need to do this every time I want to debug my code activity?)
8. Reset IIS.
9. Press "Start" in visual studio so it deploys, activates and supposedly attaches the debugger (which it doesn't).

What other steps do I need to take to debug the workflow? What am I missing?

Here's a link to a simple visual studio project I'm working on, hopefully it will help explain the problem. I've also created a list instance and had the workflow attach itself automatically to the list in the linked project.

NOTE: I am not using SharePoint designer. I am also not using code to deploy the workflow. This is a declarative, XAML visual studio workflow with a code activity in it.