Ah I see:
- You don't need to include a reference in your index.html to your formatter
- Since your formatter class is in a /util folder, you should declare it as "util.my.Formatter", and in your Controller add a jQuery.sap.require("util.my.Formatter") reference at the top
- Same in your view; instead of referencing it as "my.Formatter.getName", use "util.my.Formatter.getName"