Use json as included in Python SL #3142

We use json as included in Python. This will make Sugar dependent on
Python 2.6 and Python 2.7 to have the highest JSON performance.

Signed-off-by: Simon Schampijer <simon@laptop.org>

src/sugar3/activity/activity.py

@@ -56,6 +56,7 @@ from hashlib import sha1
 from functools import partial
 import StringIO
 import cairo
+import json
 
 from gi.repository import GConf
 from gi.repository import Gtk
@@ -64,7 +65,6 @@ from gi.repository import GObject
 import dbus
 import dbus.service
 from dbus import PROPERTIES_IFACE
-import cjson
 from telepathy.server import DBusProperties
 from telepathy.interfaces import CHANNEL, \
                                  CHANNEL_TYPE_TEXT, \
@@ -724,8 +724,8 @@ class Activity(Window, Gtk.Container):
 
         buddies_dict = self._get_buddies()
         if buddies_dict:
-            self.metadata['buddies_id'] = cjson.encode(buddies_dict.keys())
-            self.metadata['buddies'] = cjson.encode(self._get_buddies())
+            self.metadata['buddies_id'] = json.dumps(buddies_dict.keys())
+            self.metadata['buddies'] = json.dumps(self._get_buddies())
 
         preview = self.get_preview()
         if preview is not None: