setup.py: bring back the block that installs addons
setup.py: bring back the block that installs addons

Was removed in d6fc9237a62a4, but is necessary for the creation of distro
packages.

MarkusTeufelberger/openobject-server,splbio/openobject-server,MarkusTeufelberger/openobject-server,vnc-biz/openerp-server,ovnicraft/openerp-server,gisce/openobject-server,gisce/openobject-server,MarkusTeufelberger/openobject-server,splbio/openobject-server,ovnicraft/openerp-server,vnc-biz/openerp-server,splbio/openobject-server,gisce/openobject-server