Increase size of first disk for slave nodes in VirtualBox

When the Ceph role is selected 16GB isn't enough to satisfy
the minimum space requirements for all volume groups.

Change-Id: I24d51c64b183455dceffbf8cb8813395aaf46142
Related-Bug: #1248662
Update savanna packages list

Change-Id: I7adeb043f378fb312696ac67cd1f8116c05a4e89
Merge "Update savanna packages list"
Refactoring system tests on python-proboscis

Change-Id: Iae82bece4923db898836db405cddc81f94526913