Add optional links to a dependency

See gh-163

initializr-generator/src/main/groovy/io/spring/initializr/metadata/Dependency.groovy

@@ -84,13 +84,15 @@ class Dependency extends MetadataElement {
 
 	@JsonIgnore
 	String versionRequirement
-	
+
 	private VersionRange range
 
 	String bom
 
 	String repository
 
+	List<Link> links = []
+
 	@JsonInclude(JsonInclude.Include.NON_DEFAULT)
 	int weight
 

initializr-generator/src/main/groovy/io/spring/initializr/metadata/Link.groovy

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2012-2015 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.spring.initializr.metadata
+
+/**
+ * @author Dave Syer
+ *
+ */
+class Link {
+	
+	String id
+	
+	URL url
+	
+	String description
+
+}