The assignee of any bond, note, account, or writing, not negotiable, or other chose in action arising out of contract or injury to personal or real property, may maintain thereupon any action in his own name, without the addition of "assignee," which the original obligee, promisee, payee, contracting party, or owner of such chose in action might have brought; but shall allow all just defenses and sets-off, not only against himself but against the assignor, before the defendant had notice of the assignment. In every such action the plaintiff may unite claims payable to him individually with those payable to him as such assignee, provided it be otherwise proper to join them. But nothing in this section shall be construed to make assignable any right of action not otherwise assignable.