FEATURE: Anonymize User. A way to remove a user but keep their topics and posts.

app/services/username_changer.rb

@@ -0,0 +1,23 @@
+class UsernameChanger
+
+  def initialize(user, new_username, actor=nil)
+    @user = user
+    @new_username = new_username
+    @actor = actor
+  end
+
+  def self.change(user, new_username, actor=nil)
+    self.new(user, new_username, actor).change
+  end
+
+  def change
+    if @actor && @actor != @user
+      StaffActionLogger.new(@actor).log_username_change(@user, @user.username, @new_username)
+    end
+
+    # future work: update mentions and quotes
+
+    @user.username = @new_username
+    @user.save
+  end
+end