Avoid Jenkins' CodeSniffer warnings for Userlogin

Avoid Jenkins' CodeSniffer warnings for Userlogin

Change property declarations from "var" to "public". This eliminates the
 46 | ERROR | The var keyword must not be used to declare a property
warnings from Jenkins CI, e.g.
https://integration.mediawiki.org/ci/job/mediawiki-core-phpcs-HEAD/1565/console

http://php.net/manual/en/language.oop5.properties.php says
  "If you declare a property using var instead of one of public,
protected, or private, then PHP 5 will treat the property as if it had
been declared as public."
, so this should be a no-op.

Change-Id: I754ccea018f95421bfe3f7b04e3ab3a6d9b407e3