Update notes for submitted changes

* exercices: aggregates needs to be more flexible
Update notes for submitted changes

* Fix bugs for installing docker, bug #1237581.   -The change in install_docker.sh corrects a typo ('=' should be '-').    This typo resutls in 'unable to locate the packet' error when executing apt-get.
Update notes for submitted changes

* XenAPI: Get pool default SR rather than "Local storage"