Use Hometown gem for SWT leak hunter

Extraction of all the functionality that started life in Shoe's SWT leak
hunter have made their way over to the hometown gem. Given that, this
commit just uses hometown, since it's 1) actually tested 2) I'm planning
on maintaining it and 3) less code for Shoes, hurray!
add link to hometown gem site for convenience [ci skip]
Merge pull request #769 from shoes/hometown_for_leak_tracking

Use Hometown gem for SWT leak hunter