conpaas image creation scripts: fix "unary operator expected" error when $arch is not defined


git-svn-id: svn://svn.forge.objectweb.org/svnroot/contrail/trunk/conpaas@5514 ef35cc4a-2640-4bbf-98bc-65920db7d8ae
conpaas: install wget in core image creation script

git-svn-id: svn://svn.forge.objectweb.org/svnroot/contrail/trunk/conpaas@5515 ef35cc4a-2640-4bbf-98bc-65920db7d8ae
conpaas image creation scripts: add MySQL Galera service


git-svn-id: svn://svn.forge.objectweb.org/svnroot/contrail/trunk/conpaas@5516 ef35cc4a-2640-4bbf-98bc-65920db7d8ae