Upgrade build

No need to add an sbt plugin release resolver, re-set the bintray
settings (those are the defaults), and upgrade to the sbt 1.2+ way of
defining an sbt plugin.

Author: dwijnand

build.sbt

@@ -1,4 +1,4 @@
-sbtPlugin         := true
+enablePlugins(SbtPlugin)
 
 git.baseVersion   := "2.0.0"
 versionWithGit
@@ -7,10 +7,5 @@ name                := "sbt-scala-module"
 organization        := "org.scala-lang.modules"
 licenses            := Seq(("Apache-2.0", url("https://www.apache.org/licenses/LICENSE-2.0")))
 
-resolvers           += Classpaths.sbtPluginReleases
-bintrayRepository   := "sbt-plugins"
-bintrayOrganization := None
-publishMavenStyle   := false
-
 addSbtPlugin("com.typesafe.sbt" % "sbt-osgi" % "0.9.4")
 addSbtPlugin("com.typesafe" % "sbt-mima-plugin" % "0.3.0")