Change default feature groups to empty array

Feature groups should always be an array, not a dict.
Also, save() method should save data as an array too.

Change-Id: Ifda6503f7083a3749fa05ca838fe2d3e3e29ecb3
Closes-Bug: #1556923

fuelmenu/modules/feature_groups.py

@@ -90,13 +90,14 @@ class feature_groups(urwid.WidgetWrap):
                 log.warning("unexpected error: %s", e.message)
 
     def save(self, responses):
-        settings = self.parent.settings
-        newsettings = ModuleHelper.make_settings_from_responses(responses)
-        settings.merge(newsettings)
-
-        for setting in self.defaults:
+        newsettings = {}
+        for setting in responses:
             part1, part2 = setting.split("/")
-            self.defaults[setting]["value"] = part2 in settings[part1]
+            if part1 not in newsettings:
+                newsettings[part1] = []
+            if responses[setting]:
+                newsettings[part1].append(part2)
+        self.parent.settings.merge(newsettings)
 
     def cancel(self, button):
         ModuleHelper.cancel(self, button)

fuelmenu/settings.yaml

@@ -65,4 +65,4 @@ BOOTSTRAP:
     suite: "mos${mos_version}-holdback"
     type: "deb"
 PRODUCTION: docker
-FEATURE_GROUPS: {}
+FEATURE_GROUPS: []