- form reformatted as a grid (using class form-row)
- when replacing a version
  - select the version used for starting the current sandbox
  - initialise the "changelog" field with the previous changelog
    of the version being replaced
- when creating a new version
  - initialise the "changelog" field with an empty value
  - raise an error if the entered version already exists
    (prevents accidental overwriting by the user)
- report commit result in a flash message