[kameleon] Import Debian 8 template + fix gliches

- fix syslinux mbr location -> changed with last package version
- update vbox version for additions -> required to compile on Debian 8
- load loop module (not already done on Debian 8) and mount ro
[debian8] Create deb_debian8_pgsql (copy from debian7)
[debian8] change network
[debian8] fix postgresql version + add netbase as required by nfsd

netbase should be a dep of nfs-kernel-server (debian bug ?)
or is a base package that should be installed on any system (kameleon
bug? )
[debian8] Fixed extlinux mbr path
[debian8] Pull systemd from debootstrap
Make debootstrap with default variant
[kameleon] update and import debian+vagrant templates
[kameleon] renaming recipes
[debian8] remove netbase, not needed anymore
[kameleon] make recipes lighter

Removed most of deboostrap additional packages: everything else should
now come from debootstrap default setup.

To watch: might need to add back the acpi stuff.
[misc] fix golden VM name, after VM renamed in recipes
[debian8] add apt-get upgrade to keep in sync with debian testing
[debian8] add workaround needed for up to oar-2.5.4~rc5-1
[debian8] remove workarounds: bug fixed in 2.5.4~rc7-1
[debian8] remove double apt-get update
[kameleon] rename centos6.5 -> centos6
[debian8] add OAR_APT_OPTS to OAR apt-get commands
[centos6] rename vagrant base box -> centos6
[misc] add vagrant-snapshot.sh: snapshoting all VMs at once