(bug 40541) Fixed $wgSecureLogin functionality.

(bug 40541) Fixed $wgSecureLogin functionality.

* Added parameter to login link so that wpStickHTTPS
  is set to true by default when the user is coming
  from HTTPS.
* Added redirect in Special:Userlogin so that when
  $wgSecureLogin is enabled it automatically redirects
  to HTTPS.
* Adjusted User::setCookies() to add a parameter for
  forcing secure/insecure cookies, and then added the
  appropriate argument to Special:Userlogin so that
  cookies are set appropriately.

Change-Id: I17ac68014840daa47bfd4768e978e9ff2edb00db