Update specs2 to 4.0.0
Update specs2 to 4.0.0

ChristopherDavenport/http4s,rossabaker/http4s,aeons/http4s,rossabaker/http4s,aeons/http4s,reactormonk/http4s,aeons/http4s,ChristopherDavenport/http4s,reactormonk/http4s,ChristopherDavenport/http4s,reactormonk/http4s,http4s/http4s