[FIX] ir_attachment filestore read on windows

lp bug: https://launchpad.net/bugs/1131272 fixed

bzr revid: al@openerp.com-20130227221943-izxnxulg0picimez

openerp/addons/base/ir/ir_attachment.py

@@ -83,7 +83,7 @@ class ir_attachment(osv.osv):
             if bin_size:
                 r = os.path.getsize(full_path)
             else:
-                r = open(full_path).read().encode('base64')
+                r = open(full_path,'rb').read().encode('base64')
         except IOError:
             _logger.error("_read_file reading %s",full_path)
         return r