HYDRASIR-293 As a proxy, I should not be listed as a contributor

    1. The proxy, i.e. current user, is not automatically added as a contributor.
    2. 'Ownership' field does not default to 'Myself', but instead defaults to blank.
    3. 'Ownership' field is now required so user must make a selection.
    4. Hook up the "Ownership" field with javascript/jquery which will update the new contributor control and force a click of its Add button to add that person as a contributor.
    5. Add proxy_deposit_spec.rb spec test file.
Merge pull request #496 from projecthydra/feature/HYDRASIR-293_with_275

HYDRASIR-293 As a proxy, I should not be listed as a contributor