login options: remove the ;[options] support from CURLOPT_USERPWD

To avoid the regression when users pass in passwords containing semi-
colons, we now drop the ability to set the login options with the same
options. Support for login options in CURLOPT_USERPWD was added in
7.31.0.

Test case 83 was modified to verify that colons and semi-colons can be
used as part of the password when using -u (CURLOPT_USERPWD).

Bug: http://curl.haxx.se/bug/view.cgi?id=1311
Reported-by: Petr Bahula
Assisted-by: Steve Holme
Signed-off-by: Daniel Stenberg <daniel@haxx.se>