Currently a lot of people are automatically added as followers of expense
reports. However most of them (managers notably) can choose what to follow
using subtypes on the department. We should avoid adding too much people
as following records should stay an active choice made by users.
From now on auto subscription works on
* employee of the expense report, if he has an user;
* responsible of the expense report, that is the expense manager or the
manager of the employee;
Expense report creator is not follower of the expense report by default
anymore, as previous values should be sufficient to ensure people having
to work on the expense report are already followers.
This commit is related to task ID 1819541.
Thibault Delavallée
742476fb20