Add the following to your user key bindings.
{ "keys": ["ctrl+n"], "command": "move", "args": {"by": "lines", "forward": false} },
{ "keys": ["ctrl+p"], "command": "move", "args": {"by": "lines", "forward": true} }
If you are an emacs user, you may also be interested in trying out https://github.com/grundprinzip/sublemacspro