admin/myprofile layout after validation (fixes #2644)

Broke because the <form> tag was returned, while
the client logic was expecting the whole <div> including the <form>.
Fixed to display the button bar at the bottom,
and tested with validation errors as well as switching from/to
the panel via ajax.
Merge pull request #2647 from chillu/pulls/2644-myprofile-layout

admin/myprofile layout after validation (fixes #2644)