recorder.warc_test: WIP Stub in FTP recorder test

[ci skip]
recorder.warc: WIP FTP WARC recording.

[ci skip]
ftp.client: Implement recorder on data stream read
recorder.warc: Append newline to log as needed.
urlfilter.FollowFTPFilter: Handle case where referrer is None
Implement --follow-ftp option.
ftp.client: Adjust FTP password to match Wget
ftp: Handle bad directory listing case.
Implement WARC logging data connection events
recorder.warc: Backport textwrap.indent
ftp.client_test: Update test due to updated test FTP server
Merge branch 'develop' into issue/23_ftp_2
Merge branch 'issue/23_ftp_2' into develop
doc: Update changelog & terse_options w/ experimental FTP support

Closes chfoo/wpull#23