apply license gradle plugin

This PR applies the [Gradle License Plugin](https://github.com/hierynomus/license-gradle-plugin). The plugin contributes a gradle task `downloadLicenses` which generates a license report of every dependencies.

The plugin is applied to subprojects and the root project to get an aggregated report.

./gradlew downloadLicenses
open build/reports/license/license-dependency.html

build.gradle

@@ -11,12 +11,59 @@ buildscript {
         classpath "javax.xml.bind:jaxb-api:$jaxbApiVersion"
         classpath "com.sun.xml.bind:jaxb-impl:$jaxbImplVersion"
         classpath "org.codehaus.groovy.modules.http-builder:http-builder:0.7.2"
+        classpath("gradle.plugin.com.hierynomus.gradle.plugins:license-gradle-plugin:0.16.1")
     }
 }
 
 import static groovyx.net.http.ContentType.*
 
 apply plugin: 'idea'
+apply plugin: 'com.github.hierynomus.license-report'
+
+List<String> licenseExclusions = [
+        "org.grails.grails-bom",
+        "org.grails:grails-bootstrap",
+        "org.grails:grails-codecs",
+        "org.grails:grails-console",
+        "org.grails:grails-core",
+        "org.grails:grails-databinding",
+        "org.grails:grails-dependencies",
+        "org.grails:grails-docs",
+        "org.grails:grails-encoder",
+        "org.grails:grails-gradle-model",
+        "org.grails:grails-logging",
+        "org.grails:grails-plugin-codecs",
+        "org.grails:grails-plugin-controllers",
+        "org.grails:grails-plugin-databinding",
+        "org.grails:grails-plugin-datasource",
+        "org.grails:grails-plugin-domain-class",
+        "org.grails:grails-plugin-i18n",
+        "org.grails:grails-plugin-interceptors",
+        "org.grails:grails-plugin-mimetypes",
+        "org.grails:grails-plugin-rest",
+        "org.grails:grails-plugin-services",
+        "org.grails:grails-plugin-url-mappings",
+        "org.grails:grails-plugin-validation",
+        "org.grails:grails-spring",
+        "org.grails:grails-test",
+        "org.grails:grails-test-suite-base",
+        "org.grails:grails-test-suite-persistence",
+        "org.grails:grails-test-suite-uber",
+        "org.grails:grails-test-suite-web",
+        "org.grails:grails-web",
+        "org.grails:grails-web-boot",
+        "org.grails:grails-web-common",
+        "org.grails:grails-web-databinding",
+        "org.grails:grails-web-fileupload",
+        "org.grails:grails-web-mvc",
+        "org.grails:grails-web-url-mappings",
+].collect { "${it}:${project.projectVersion}" as String}
+
+downloadLicenses {
+    includeProjectDependencies = true
+    dependencyConfiguration = 'runtimeClasspath'
+    excludeDependencies = licenseExclusions
+}
 
 ext {
     isJava8Compatible = org.gradle.api.JavaVersion.current().isJava8Compatible()
@@ -352,6 +399,12 @@ subprojects { project ->
     apply plugin: 'eclipse'
     apply plugin: 'idea'
     apply plugin: 'project-report'
+    apply plugin: 'com.github.hierynomus.license-report'
+    downloadLicenses {
+        includeProjectDependencies = true
+        dependencyConfiguration = 'runtimeClasspath'
+        excludeDependencies = licenseExclusions
+    }
 
     if (!isTestSuite) {