Merge pull request android-async-http#528 from ldiqual/bugfix/default-cast-string

Cast params to string by default

Author: smarek

Diff for: library/src/main/java/com/loopj/android/http/RequestParams.java

@@ -527,8 +527,8 @@ private List<BasicNameValuePair> getParamsList(String key, Object value) {
             for (Object nestedValue : set) {
                 params.addAll(getParamsList(key, nestedValue));
             }
-        } else if (value instanceof String) {
-            params.add(new BasicNameValuePair(key, (String) value));
+        } else {
+            params.add(new BasicNameValuePair(key, value.toString()));
         }
         return params;
     }