'Sets the special headers to use, this headers are specified in a file by
the user. The file can have multiple lines, each line should have the
following structure :
- HEADER:VALUE_OF_HEADER
:param headers_file: The filename where the additional headers are
specified
:return: No value is returned.'

def set_headers_file(self, headers_file):

    if (not headers_file):
        return
    try:
        f = open(headers_file, 'r')
    except:
        msg = 'Unable    to    open    headers    file:    "%s"'
        raise BaseFrameworkException((msg % headers_file))
    header_list = []
    for line in f:
        header_name = line.split(':')[0]
        header_value = ':'.join(line.split(':')[1:])
        header_value = header_value.strip()
        header_list.append((header_name, header_value))
    self.set_header_list(header_list)
    cfg.save('headers_file', headers_file)
