Setup JDK roots and initialize JDK_HOME in common core environment

#KT-20167 Fixed

compiler/util/src/org/jetbrains/kotlin/utils/PathUtil.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2016 JetBrains s.r.o.
+ * Copyright 2010-2017 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -121,4 +121,8 @@ object PathUtil {
     @JvmStatic
     fun getJdkClassesRoots(jdkHome: File): List<File> =
             JavaSdkUtil.getJdkClassesRoots(jdkHome, false)
+
+    @JvmStatic
+    fun getJavaHome(): File =
+            File(System.getProperty("java.home"))
 }