update_project: don't delete aggregate packages

Change-Id: Icd3643ec09d42a398ccd9f4ea22fb7f5db1c189c
Signed-off-by: Stephane Desneux <stephane.desneux@open.eurogiciel.org>
updated README

Change-Id: Icc869606baab2b69e6422d4af06433c29a9d2b92
Signed-off-by: Stephane Desneux <stephane.desneux@open.eurogiciel.org>