Add notification option for ownership assignments for projects, releases, features and requirements.

Send notification to individual when assigned as a 1) product owner, 2) release owner, 3) assigned to a feature, or 4) assigned to a requirement in the same way someone is notified when assigned to a To-Do. This could possibly be an option rather than an absolute, such as a "notify of assignment" type of an option. We are finding that people, although they could view in their work overview screen, sometimes are not aware when they are assigned officially to a product, release, feature, or requirement in the same way they are when they are assigned to a To-do.