Issue #73 Rename IdeaNotification model
Issue #73 Change parameters of send method in IdeaNotifications
Issue #73 Rename table user_notifications_users
Merge branch 'C1_AminaZoheir_#73_Notifications_migrations' into C1_AminaZoheir_#73_Notification_Module
Issue #73 Fix some errors in notification models

1. Add missing .save at the enf os send_notification method
2. Correct class names