comments: allow new users to comment.

Remove the rule that users less than a week old can't leave comments.

test/functional/comment_votes_controller_test.rb

@@ -5,7 +5,6 @@ class CommentVotesControllerTest < ActionDispatch::IntegrationTest
     setup do
       CurrentUser.user = @user = create(:user)
       CurrentUser.ip_addr = "127.0.0.1"
-      Danbooru.config.stubs(:member_comment_time_threshold).returns(1.week.from_now)
       @comment = create(:comment)
     end