Fixed issue in activity stream #3705

Refer Issue: #25

Review ID: 1983001
Merge pull request #26 from tarunbhardwaj/task-3705

Fixed issue in activity stream #3705
Merge branch 'hotfix/3.0.1.1' into develop
Replacing all _json(self) to serialize(self, purpose=None) #3895

Review ID - 2733001