Redmine

After r21073 was introduced application helper has multiple methods to render user/group links:

• link_to_user
• link_to_principal
• link_to_group

The link_to_principal method combines the functionality of the other two. They don't have much use right now. I propose to unify all 3 methods in one.

An attached patch removes link_to_user and link_to_group methods and adds two aliases to link_to_principal (user and group respectively).

link_to_group was used to redirect admin user to edit group page which is obsolete since all users have access to show group page and there is an edit link for admin.

Patch also adds a new test to confirm edit link presence for admins.