Remove append feature from get_roles
    
    Feature does not serve any practical purpose, the only script having
    used it, test_roles.py, is better served by appending the needful by
    itself.
    Removing this feature makes maintaining and extending the roles
    script easier by having less surrounding logic to consider.
    
    Signed-off-by: Georg Pfuetzenreuter <mail@georg-pfuetzenreuter.net>