The introduction of page-server send mode have broken the lazy dump because
instead of using existing pstree, the page server now tries to recreate the
pstree from the images.
Adding lazy_dump parameter to cr_page_server resolves this issue.

travis-ci: success for lazy-pages: fix lazy dump
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Acked-by: Adrian Reber <areber@redhat.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>