Adds Ivy to the classpath so Groovy scripts can use @grab. Fixes #1. …

…Also improves/fixes the build some.

build.gradle

@@ -8,13 +8,15 @@ dependencies {
 
 task copyToWrapperDir(type: Copy) {
     description 'Copies the Groovy wrapper binary to its runtime home with the Graddle wrapper'
-    from "$buildDir/libs/groovy-wrapper.jar"
+    dependsOn build
+    from jar
     into 'gradle/wrapper'
+    rename "-${version}", ""
 }
 
 task distZip(type: Zip) {
     description 'Makes a zip file containing just the Groovy wrapper binary and scripts'
-    dependsOn build
+    dependsOn copyToWrapperDir
     from 'gradle/wrapper/groovy-wrapper.jar'
     from 'groovyw'
     from 'groovyw.bat'

src/main/java/org/gradle/wrapper/GroovyBootstrapMainStarter.java

@@ -25,7 +25,8 @@ public class GroovyBootstrapMainStarter extends BootstrapMainStarter {
     @Override
     public void start(String[] args, File gradleHome) throws Exception {
         File groovyJar = findGroovyJar(gradleHome);
-        URLClassLoader contextClassLoader = new URLClassLoader(new URL[]{groovyJar.toURI().toURL()}, ClassLoader.getSystemClassLoader().getParent());
+        File ivyJar = findIvyJar(gradleHome);
+        URLClassLoader contextClassLoader = new URLClassLoader(new URL[]{groovyJar.toURI().toURL(),ivyJar.toURI().toURL()}, ClassLoader.getSystemClassLoader().getParent());
         Thread.currentThread().setContextClassLoader(contextClassLoader);
         Class<?> mainClass = contextClassLoader.loadClass("groovy.ui.GroovyMain");
         Method mainMethod = mainClass.getMethod("main", String[].class);
@@ -43,4 +44,13 @@ private File findGroovyJar(File gradleHome) {
         }
         throw new RuntimeException(String.format("Could not locate the Groovy JAR in Gradle distribution '%s'.", gradleHome));
     }
+
+    private File findIvyJar(File gradleHome) {
+        for (File file : new File(gradleHome, "lib/plugins").listFiles()) {
+            if (file.getName().matches("ivy-.*\\.jar")) {
+                return file;
+            }
+        }
+        throw new RuntimeException(String.format("Could not locate the Ivy JAR in Gradle distribution '%s'.", gradleHome));
+    }
 }