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>

tests/data/test83

@@ -50,7 +50,7 @@ http-proxy
 HTTP over proxy-tunnel with site authentication
  </name>
  <command>
-http://test.83:%HTTPPORT/we/want/that/page/83 -p -x %HOSTIP:%PROXYPORT --user iam:myself
+http://test.83:%HTTPPORT/we/want/that/page/83 -p -x %HOSTIP:%PROXYPORT --user 'iam:my:;self'
 </command>
 </client>
 
@@ -69,7 +69,7 @@ Proxy-Connection: Keep-Alive
 </proxy>
 <protocol>
 GET /we/want/that/page/83 HTTP/1.1
-Authorization: Basic aWFtOm15c2VsZg==
+Authorization: Basic aWFtOm15OjtzZWxm
 User-Agent: curl/7.10.7-pre2 (i686-pc-linux-gnu) libcurl/7.10.7-pre2 OpenSSL/0.9.7a zlib/1.1.3
 Host: test.83:%HTTPPORT
 Accept: */*