Let activities extend their own path

shell/conf/ActivityRegistry.py

@@ -74,7 +74,7 @@ class _ActivityRegistry:
 
 	def __init__(self):
 		self._activities = []
-		self.scan_directory(env.get_activities_dir())
+		self.scan_directory(env.get_activity_info_dir())
 
 	def get_activity(self, activity_id):
 		"""Returns an activity given his identifier"""

shell/sugar-activity

@@ -17,6 +17,9 @@
 # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 
 import sys
+import os
+
+sys.path.insert(0, env.get_activities_dir())
 
 from sugar.activity import ActivityFactory