(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