Change Pretend Mode Quickly

Currently it is possible to change the user's role by the space property 'pretend-being-a' which has to be set as a space property on the user's Confluence homepage.

This is not very convenient since the page has to be edited and saved. Changes are also stored in the page history, which may be distracting.

We should consider to add an action to quickly change roles. We have to keep in mind that there may be additional roles (than writer, printer and reader) in the future.