Clean up: Declare variables with public instead of var

Clean up: Declare variables with public instead of var

Variables in classes should be declared using public $foo
instead of var $foo for various reasons. As we require PHP 5.3
we don't have to take care about that PHP4 left over, but can
get rid of it in favour of the more clear and better readable
public.
See also: http://php.net/manual/en/language.oop5.visibility.php
(Divided into several commits to keep reviewable)

Change-Id: Ic723d0347ab2e3c78bc0097345c68bbee3dc035a