[7.0] do not update inherit groups

[Ceferino Cuevas]

1) Steps to reproduce the issue you have observed
Create a Users/Group who inherits all managers groups access rights.
Create a Users/Users and subscribe it to the new group. (The new user have managers access rights in all the applications).
Edit the new User and remove it from the new group.
Review the role on the applications.

Can find a demonstrative video here:
http://www.youtube.com/watch?v=0sxETE_onLo

2) The result you observed
At the moment of removing the user from the managers group do not remove the user from all the applications who was inherited in first place.

 3) The result you expected
All the groups Inherited should be removed too.

4) The platform your are using
Ubuntu 12.04

 5) The OpenERP version
OpenERP 7.0
addons/7.0
addons: Revno 9195
server: Revno 4995
web: 3942