Reads and returns the contents of a file

def _read_file(folder, filename):
    '''
    Reads and returns the contents of a file
    '''
    path = os.path.join(folder, filename)
    try:
        with salt.utils.files.fopen(path, 'rb') as contents:
            return salt.utils.data.decode(contents.readlines())
    except (OSError, IOError):
        return ''