allow empty POST bodies

Author: rogerhu

example/src/main/java/com/codepath/example/TestActivity.java

@@ -49,7 +49,20 @@ public void onFailure(int statusCode, Headers headers, String response, Throwabl
             }
         });
 
-        cp.post("https://api.thecatapi.com/v1/images/search", "", new JsonHttpResponseHandler() {
+        cp.post("https://api.thecatapi.com/v1/images/search", new JsonHttpResponseHandler() {
+            @Override
+            public void onSuccess(int statusCode, Headers headers, JSON json) {
+                Log.d("DEBUG", json.toString());
+
+            }
+
+            @Override
+            public void onFailure(int statusCode, Headers headers, String response, Throwable throwable) {
+
+            }
+        });
+
+        cp.post("https://api.thecatapi.com/v1/images/search", "test", new JsonHttpResponseHandler() {
             @Override
             public void onSuccess(int statusCode, Headers headers, JSON json) {
                 Log.d("DEBUG", json.toString());

library/src/main/java/com/codepath/asynchttpclient/AsyncHttpClient.java

@@ -86,6 +86,10 @@ public void post(String url, RequestParams requestParams, RequestHeaders request
         okHttpClient.newCall(request).enqueue(callback);
     }
 
+    public void post(String url, AbsCallback callback) {
+        this.post(url, null, null, "", callback);
+    }
+
     public void post(String url, String body, AbsCallback callback) {
         this.post(url, null, null, body, callback);
     }