Add sftp subsystem debian (#3)

* Add map for debian

openssh/map.jinja

@@ -75,6 +75,9 @@ that differ from whats in defaults.yaml
     'Arch': {
         'Subsystem': 'sftp /usr/lib/ssh/sftp-server',
     },
+    'Debian': {
+        'Subsystem': 'sftp /usr/lib/openssh/sftp-server',
+    },
     'RedHat': {
         'Subsystem': 'sftp /usr/libexec/openssh/sftp-server',
     },