Added javadoc for all the helper classes in SDN-IP.

Also changed a couple of names to better reflect the usage or comply with
naming standards:
  in IBgpRouteService.java: getBGPdRestIp -> getBgpdRestIp
  in Prefix.java: MAX_BYTES -> ADDRESS_LENGTH

Change-Id: Id23b6bb077d79d671d21e2490ab410f322d7c166
diff --git a/src/main/java/net/onrc/onos/apps/bgproute/RestClient.java b/src/main/java/net/onrc/onos/apps/bgproute/RestClient.java
index f1fc370..c7ff195 100644
--- a/src/main/java/net/onrc/onos/apps/bgproute/RestClient.java
+++ b/src/main/java/net/onrc/onos/apps/bgproute/RestClient.java
@@ -12,18 +12,30 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+/**
+ * A simple HTTP client. It is used to make REST calls to the BGPd process.
+ */
 public final class RestClient {
     private static final Logger log = LoggerFactory.getLogger(RestClient.class);
 
+    /**
+     * Default constructor.
+     */
     private RestClient() {
         // Private constructor to prevent instantiation
     }
 
-    public static String get(String str) {
+    /**
+     * Issues a HTTP GET request to the specified URL.
+     *
+     * @param strUrl the URL to make the request to
+     * @return a String containing any data returned by the server
+     */
+    public static String get(String strUrl) {
         StringBuilder response = new StringBuilder();
 
         try {
-            URL url = new URL(str);
+            URL url = new URL(strUrl);
             HttpURLConnection conn = (HttpURLConnection) url.openConnection();
             conn.setConnectTimeout(2 * 1000); // 2 seconds
             conn.setRequestMethod("GET");
@@ -36,7 +48,7 @@
             }
 
             if (!conn.getContentType().equals("application/json")) {
-                log.warn("The content received from {} is not json", str);
+                log.warn("The content received from {} is not json", strUrl);
             }
 
             BufferedReader br = new BufferedReader(new InputStreamReader(
@@ -60,10 +72,15 @@
         return response.toString();
     }
 
-    public static void post(String str) {
+    /**
+     * Issues a HTTP POST request to the specified URL.
+     *
+     * @param strUrl the URL to make the request to
+     */
+    public static void post(String strUrl) {
 
         try {
-            URL url = new URL(str);
+            URL url = new URL(strUrl);
             HttpURLConnection conn = (HttpURLConnection) url.openConnection();
             conn.setDoOutput(true);
             conn.setRequestMethod("POST");
@@ -84,10 +101,15 @@
         }
     }
 
-    public static void delete(String str) {
+    /**
+     * Issues a HTTP DELETE request to the specified URL.
+     *
+     * @param strUrl the URL to make the request to
+     */
+    public static void delete(String strUrl) {
 
         try {
-            URL url = new URL(str);
+            URL url = new URL(strUrl);
             HttpURLConnection conn = (HttpURLConnection) url.openConnection();
             conn.setRequestMethod("DELETE");
             conn.setRequestProperty("Accept", "application/json");