Add attachment support

Author: RuairiK

intercom-java/src/main/java/io/intercom/api/Reply.java

@@ -9,6 +9,9 @@ class Reply<T extends Replier> extends TypedData {
 
     @JsonProperty("body")
     private String body;
+    
+    @JsonProperty("attachment_urls")
+    private String[] attachmentUrls;
 
     @JsonProperty("from")
     T from;
@@ -29,6 +32,11 @@ public Reply<T> setBody(String body) {
         this.body = body;
         return this;
     }
+    
+    public Reply<T> setAttachmentUrls(String[] attachmentUrls) {
+    	this.attachmentUrls = attachmentUrls;
+    	return this;
+    }
 
     T getFrom() {
         return from;

intercom-java/src/test/java/io/intercom/api/ConversationTest.java

@@ -58,6 +58,13 @@ public void testAdminReply() {
         } catch (InvalidException e) {
             fail();
         }
+        
+        adminReply.setAttachmentUrls(new String[]{"http://www.example.com/attachment.jpg"});
+        try {
+            Conversation.validateAdminReplyRequest(adminReply);
+        } catch (InvalidException e) {
+            fail();
+        }
     }
 
     @Test