sbt-web enhancements for http4s

Latest version

[![sbt-http4s-web Scala version support](https://index.scala-lang.org/ahjohannessen/sbt-http4s-web/sbt-http4s-web/latest.svg](https://index.scala-lang.org/ahjohannessen/sbt-http4s-web/sbt-http4s-web)

sbt 1.0 badge

[![sbt-http4s-web Scala version support](https://index.scala-lang.org/ahjohannessen/sbt-http4s-web/sbt-http4s-web/latest-by-scala-version.svg?platform=sbt1.0](https://index.scala-lang.org/ahjohannessen/sbt-http4s-web/sbt-http4s-web)