version up : stunnel 5.00.
[component/slapos] Pin PyOpenSSL Version

Use more recently versions of PyOpenSSL requires cryptograpic egg. The cryptograpic is
incompatible with package generation because it don't cache files in the right way.
Merge remote-tracking branch 'origin/master' into erp5-component
version up : percona-toolkit 2.2.7.