[trunk]: Need to find a proper way to allow installation of modules(which rely on this group) even if "Whole Company" group is deleted.

[Ravi Gohil (OpenERP)]

Trunk revision info,
addons: 8973
server: 4992
web: 3883

If some user accidently deleted the group "Whole Company"(inserted through mail/data/mail_group_data.xml, having xml_id "group_all_employees") or deleted it as he would not wanted to use it and if he tries to install some module, he wont be able to do so due to a traceback which would say,

File "/home/rgo/workspace/trunk/openobject-server/openerp/addons/base/ir/ir_model.py", line 861, in _get_id
    raise ValueError('No such external ID currently defined in the system: %s.%s' % (module, xml_id))
ParseError: "No such external ID currently defined in the system: mail.group_all_employees" while parsing /home/rgo/workspace/trunk/openobject-addons/account_voucher/account_voucher_data.xml:6, near ...

In this case, alternative solution would be the upgradation of the mail module, but it might add unnecessary data.

There are as many as 17 modules dependent on this group which a user wont be able to install if this group is deleted.

This design needs some improvement in future version which should allow installation of module even if this group is deleted.

Thanks.