Use params[:merge_commit_message] in MergeRequestController for automerge

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/controllers/projects/merge_requests_controller.rb

@@ -123,7 +123,7 @@ class Projects::MergeRequestsController < Projects::ApplicationController
 
     if @merge_request.opened? && @merge_request.can_be_merged?
       @merge_request.should_remove_source_branch = params[:should_remove_source_branch]
-      @merge_request.automerge!(current_user)
+      @merge_request.automerge!(current_user, params[:merge_commit_message])
       @status = true
     else
       @status = false