Merge pull request #523 from avsm/master

jenkis updates
Added a check for interactivity before shell completion initialization
Using .zshrc instead of .profile for zsh users
Merge pull request #526 from AltGr/master

Fixed shell integration with some setups (.profile loaded early, zsh...)
Fix #527
Merge branch 'master' of github.com:OCamlPro/opam
Fix release target
Update CHANGES
Fix the creation of the full archive
Fix #529

'cp -a' is not standard
jenkins: add libvirt
jenkins: updates