Support backward compatibility with gradle-script-kotlin 0.2.0, some refactoring

idea/idea-core/src/org/jetbrains/kotlin/idea/core/script/gradleScriptTemplateProvider.kt

@@ -35,7 +35,9 @@ class GradleScriptTemplateProvider(project: Project, gim: GradleInstallationMana
             gradleLibsPath?.listFiles { file -> file.extension == "jar" && depLibsPrefixes.any { file.name.startsWith(it) } }
                 ?.map { it.canonicalPath }
                 ?: emptyList()
-    override val environment: Map<String, Any?>? = mapOf("gradleHome" to gradleHome)
+    override val environment: Map<String, Any?>? = mapOf(
+            "gradleHome" to gradleHome,
+            "projectRoot" to (project.basePath ?: project.baseDir.canonicalPath )?.let { File(it) })
 
     companion object {
         private val depLibsPrefixes = listOf("gradle-script-kotlin", "gradle-core")