Revert "slapos stack: use temporarily old version of slapos.core."

This reverts commit f2e57a03840678e86d478930e7ea4cc7b9202bb0.
slapos stack: use slapos.core 1.3.3.
version up : firefox 33.1.
version up : gnutls 3.2.20.
version up : LibreOffice 4.3.4.1.
version up eggs.
version up : percona-toolkit 2.2.12.