Gradle scripts should use `plugins` block

It was de-incubated (promoted) in Gradle 5.0
and in particular it can't contain duplicate IDs.

build.gradle

@@ -1,21 +1,14 @@
-buildscript {
-  repositories {
-    maven {
-      url 'https://repox.jfrog.io/repox/plugins.gradle.org/'
-    }
-  }
-  dependencies {
-    // Ordered alphabeticly to avoid duplication
-    classpath 'com.github.ben-manes:gradle-versions-plugin:0.28.0'
-    classpath 'com.github.jengelman.gradle.plugins:shadow:5.2.0'
-    classpath 'com.google.protobuf:protobuf-gradle-plugin:0.8.12'
-    classpath 'com.github.node-gradle:gradle-node-plugin:1.5.3'
-    classpath 'gradle.plugin.nl.javadude.gradle.plugins:license-gradle-plugin:0.14.0'
-    classpath 'io.spring.gradle:dependency-management-plugin:1.0.9.RELEASE'
-    classpath 'net.rdrei.android.buildtimetracker:gradle-plugin:0.11.1'
-    classpath 'org.jfrog.buildinfo:build-info-extractor-gradle:4.15.1'
-    classpath 'org.sonarsource.scanner.gradle:sonarqube-gradle-plugin:2.8'
-  }
+plugins {
+  // Ordered alphabeticly
+  id 'com.github.ben-manes.versions' version '0.28.0'
+  id 'com.github.hierynomus.license' version '0.14.0'
+  id 'com.github.johnrengelman.shadow' version '5.2.0' apply false
+  id 'com.google.protobuf' version '0.8.12' apply false
+  id 'com.jfrog.artifactory' version '4.15.1'
+  id 'com.github.node-gradle.node' version '1.5.3' apply false
+  id 'io.spring.dependency-management' version '1.0.9.RELEASE'
+  id 'net.rdrei.android.buildtimetracker' version '0.11.0'
+  id 'org.sonarqube' version '2.8'
 }
 
 // display a summary of task durations at the end of the build

settings.gradle

@@ -1,3 +1,11 @@
+pluginManagement {
+  repositories {
+    maven {
+      url 'https://repox.jfrog.io/repox/plugins.gradle.org/'
+    }
+  }
+}
+
 rootProject.name = 'sonarqube'
 
 include 'plugins:sonar-xoo-plugin'
@@ -55,4 +63,3 @@ buildCache {
     enabled = !isCiServer
   }
 }
-