Update permissions in Django Backend to more descriptive terms

During user testing, it turned out some permission strings currently cause confusion to end-users, since they do not represent the actual field names in the UI and documentation.

Current terms and strings which should be changed:

1. note: All appearances of "note" have to relation to the UI. Replace all occurrences with "episode". (see below)
2. program | show | Can edit default playlist id field: Should be program | show | Can edit default media source.
3. program | schedule | Can edit default playlist id field: Should be program | schedule | Can edit default media source.
4. Can edit short_description field: The underscore is not consistent to other labels -> Can edit short description field
5. CBA Credentials currently stored in "user.profile" to be stored under "user.cba" -> Permission Strings sind dann "program | cba | ...".
6. Model Host renaming to Model Profile or PublicProfile. Resulting permission strings are program | profile or program | public profile |.

Since we not only want to rename the appearance of notes, but also rename the Model, we move this one to a future discussion:

• note: All appearances of "note" have to relation to the UI. Replace all occurrences with "episode".