Add api side validation and defaults for init and join requests. Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com> (cherry picked from commit fb3eb1c27ef5520571c599ead8a72b343748db39)
Signed-off-by: Daniel Nephin <dnephin@docker.com> (cherry picked from commit c544649874bfecf2e6b8a00a0b25db309d81cf94)
Signed-off-by: Daniel Nephin <dnephin@docker.com> (cherry picked from commit 595e79b805fd6e96d2e6c8876f7c9734164f5db7)