Acsone addons asynchronous batch mailings

This Module allows to send email by an asynchronous way.
It also provides a way to split huge mailing.
Those features are configurable into ir.parameter
all rights reserved isn't relevant. The licence can be shortened..

``` python
##############################################################################
#
#    Authors: Nemry Jonathan
#    Copyright (c) 2014 Acsone SA/NV (http://www.acsone.eu)
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU Affero General Public License as
#    published by the Free Software Foundation, either version 3 of the
#    License, or (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU Affero General Public License for more details.
#
#    You should have received a copy of the GNU Affero General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
##############################################################################
```