Remove scoverage sbt plugin

It doesn't work.

Author: smarter

project/plugins.sbt

@@ -8,5 +8,3 @@ addSbtPlugin("com.typesafe.sbteclipse" % "sbteclipse-plugin" % "4.0.0")
 addSbtPlugin("org.scalastyle" %% "scalastyle-sbt-plugin" % "0.8.0")
 
 addSbtPlugin("org.scala-js" % "sbt-scalajs" % "0.6.8")
-
-addSbtPlugin("org.scoverage" % "sbt-scoverage" % "1.3.5")