v0.16.0-RC2

• Move http4s-blaze-core from org.http4s.blaze to
  org.http4s.blazecore to avoid a conflict with the non-http4s
  blaze-core module.
• Change ServiceOps to operate on a Service[?, MaybeResponse].
  Give it an orNotFound that returns a Service. The
  orNotFound(a: A) overload is left for compatibility with Scala
  2.10.
• Build with Lightbend compiler instead of Typelevel compiler so we
  don't expose org.typelevel dependencies that are incompatible with
  ntheir counterparts in org.scala-lang.
• Upgraded dependencies:
  • blaze-0.12.7 (fixes eviction notice in http4s-websocket)
  • twirl-1.3.4