Fix membership shortcode for non-member users

[dparker1005]

Issue:

1. Using shortcode [membership level="0"]
2. Logged in user without a membership level tries to view the content and should be able to
3. is_user_logged_in() will be true
4. pmprobpc_memberHasAccessWithAnyLevel( $current_user->ID ) will set $hasaccess to false since the user does not have a membership level

This behavior is incorrect. If we are trying to show content to non-members, then we absolutely don't want to hide the content because this logged-in non-member don't have a level.