Android Studio下载kotlin-compiler-embeddable 非常慢， 时间长了还会报read time out
所以需要自行下载后， 把jar放到正确的位置.
https://jcenter.bintray.com/org/jetbrains/kotlin/kotlin-compiler-embeddable/1.2.31/kotlin-compiler-embeddable-1.2.31.jar https://dl.google.com/dl/android/maven2/com/android/tools/external/com-intellij/kotlin-compiler/26.2.1/kotlin-compiler-26.2.1.jar
Mac系统默认下载到：/Users/(用户名)/.gradle/caches/modules-2/files-2.1
Windows系统默认下载到：C:\Users(用户名).gradle\caches\modules-2\files-2.1
classpath “org.jetbrains.kotlin:kotlin-gradle-plugin