Rails: Use 3.2.14 release instead of 3.2 git branch
MembersController: Fix Member being destroyed when editing roles

When removing all existing roles and adding a new role, the member was
destroyed before the new roles could be added. This might be the
result from a change in rails:
https://github.com/rails/rails/commit/c2362461cdf9615d5704d6f2942921b84b854c3c
Refactor Member and MemberRole: Disallow Member.destroy

MemberRoles can't be destroyed by themselves anymore, but Member must
be asked to do this. This allows Member to have control over validating
that each Member has at least one MemberRole and over deleting the Member
itself when no MemberRole is left.

An ugly piece of code makes MemberRole.destroy raise an Exception when
something tries to call it. This should prevent people from accidentally
using it.
Add tests for added Member role methods

Might not all work
Refactor member role management

Rename methods so they make clear whether they save and/or potentially destroy a member.
Fix member not being deleted when a user was removed from a group
Update changelog

[ci skip]