Migrate to AGP 3.x syntax for README & deal with bundled JUnit 5 inconsistencies manually

Author: mannodermaus

README.md

@@ -9,7 +9,7 @@ A Gradle plugin that allows for the execution of [JUnit 5][junit5gh] unit tests
 ```groovy
 buildscript {
     dependencies {
-        classpath "de.mannodermaus.gradle.plugins:android-junit5:1.0.0-M5"
+        classpath "de.mannodermaus.gradle.plugins:android-junit5:1.0.0-M4-rev3"
     }
 }
 ```
@@ -23,10 +23,10 @@ apply plugin: "com.android.application"
 apply plugin: "de.mannodermaus.android-junit5"
 
 dependencies {
-    testCompile junitJupiter()
+    testApi junitJupiter()
 
     // (Optional) If you need "parameterized tests"
-    testCompile junitParams()
+    testApi junitParams()
 }
 ```
 
@@ -46,9 +46,9 @@ However, there are some additional properties that you can apply:
 ```groovy
 junitPlatform {
     // The JUnit Jupiter dependency version to use; matches the platform's milestone by default
-    jupiterVersion "5.0.0-M5"
+    jupiterVersion "5.0.0-M4"
     // The JUnit Vintage Engine dependency version to use; matches the platform's milestone by default
-    vintageVersion "4.12.0-M5"
+    vintageVersion "4.12.0-M4"
 }
 ```
 

android-junit5/src/main/groovy/de/mannodermaus/gradle/plugins/android_junit5/AndroidJUnitPlatformPlugin.groovy

@@ -77,11 +77,19 @@ class AndroidJUnitPlatformPlugin implements Plugin<Project> {
         project.dependencies.ext.junitJupiter = {
             def jupiterVersion = junitExtension.jupiterVersion
             def platformVersion = junitExtension.platformVersion
+            def vintageVersion = junitExtension.vintageVersion
 
             return [
                     project.dependencies.create("junit:junit:4.12"),
                     project.dependencies.create("org.junit.jupiter:junit-jupiter-api:${jupiterVersion}"),
                     project.dependencies.create("org.junit.platform:junit-platform-engine:${platformVersion}"),
+
+                    // Only needed to run tests in an Android Studio that bundles an older version
+                    // (see also http://junit.org/junit5/docs/current/user-guide/#running-tests-ide-intellij-idea)
+                    project.dependencies.create("org.junit.platform:junit-platform-launcher:$platformVersion"),
+                    project.dependencies.create("org.junit.platform:junit-platform-console:$platformVersion"),
+                    project.dependencies.create("org.junit.jupiter:junit-jupiter-engine:$jupiterVersion"),
+                    project.dependencies.create("org.junit.vintage:junit-vintage-engine:$vintageVersion"),
             ]
         }