By default, keep users in HTTPS with wgSecureLogin

Create an option to have the stickHTTPS checkbox set for all users.
When this option, $wgSecureLoginDefaultHTTPS, is true, all logged in
users will be default have their session stay in HTTPS, unless they
uncheck the box to return to the insecure option.

Change-Id: Ie846d2dc3ac5ea43bd76caa2f0eb5dbd65dbf181
Merge "By default, keep users in HTTPS with wgSecureLogin"