Formatting: Do not use \n and prefer <br> instead

It moves bbcode to bbcode_pleroma as the former is owned by kaniini
and transfering ownership wasn't done in a timely manner.

Closes: https://git.pleroma.social/pleroma/pleroma/issues/1374
Closes: https://git.pleroma.social/pleroma/pleroma/issues/1375

mix.exs

@@ -126,7 +126,7 @@ defmodule Pleroma.Mixfile do
       {:ex_aws_s3, "~> 2.0"},
       {:sweet_xml, "~> 0.6.6"},
       {:earmark, "~> 1.3"},
-      {:bbcode, "~> 0.1.1"},
+      {:bbcode_pleroma, "~> 0.2.0"},
       {:ex_machina, "~> 2.3", only: :test},
       {:credo, "~> 1.1.0", only: [:dev, :test], runtime: false},
       {:mock, "~> 0.3.3", only: :test},