Move the height/width settings to the logo component

No need for two config variables. Use the appInst config to get the
correct theme.

- The hook returns the info for a single guest, and a function to reload
  that info from the api.
- The roles of the guest are now on the roles attribute of the guest
  object instead of as its own object.
- Adding a new role now triggers a reload of the data from the api after
  the post request has completed.

Resolves: GREG-114

An api path was missing a slash and a save button did not redirect back
to the previous location