[FIX] config: correctly bootstrap data_dir

Complements the patch in 4715d18e12
in order to properly bootstrap a writeable data_dir when it is
(partially) nonexistant.
Depending on the startup parameters the data_dir might otherwise
have ended up read-only, preventing the creation of its necessary
components (session store, file store). Only the `addons` directory
of the data_dir needs to be read-only by default.

openerp/tools/config.py

@@ -560,9 +560,13 @@ class configmanager(object):
 
     @property
     def addons_data_dir(self):
-        d = os.path.join(self['data_dir'], 'addons', release.series)
+        add_dir = os.path.join(self['data_dir'], 'addons')
+        d = os.path.join(add_dir, release.series)
         if not os.path.exists(d):
             try:
+                # bootstrap parent dir +rwx
+                if not os.path.exists(add_dir):
+                    os.makedirs(add_dir, 0700)
                 # try to make +rx placeholder dir, will need manual +w to activate it
                 os.makedirs(d, 0500)
             except OSError: