New trainee cration UI

[stasel]

As a user, I should be able to create new trainees in Dojo.

Implementation details:

1. Create a new button (style=text) in the nav bar:
   

2. When clicking on "add trainee", route to /new-trainee or /trainee/new

3. Open the trainee profile in edit mode. When the user clicks 'save', it will send a POST /api/trainees request with all the fields instead of the regular PATCH. After a successful creation, the new trainee ID will be known - redirect to /trainees/<newID> as returned in the POST response from the profileURL field

4. 'cancel' button will be hidden on the edit mode.