Fixing issue #95 , by specifying UTF-8 in getBytes.

Author: Nakul Sabharwal

src/main/java/com/microsoft/graph/http/DefaultHttpProvider.java

@@ -254,7 +254,7 @@ private <Result, Body, DeserializeType> Result sendRequestInternal(final IHttpRe
                 } else {
                     logger.logDebug("Sending " + serializable.getClass().getName() + " as request body");
                     final String serializeObject = serializer.serializeObject(serializable);
-                    bytesToWrite = serializeObject.getBytes();
+                    bytesToWrite = serializeObject.getBytes("UTF-8");
 
                     // If the user hasn't specified a Content-Type for the request
                     if (!hasHeader(requestHeaders, CONTENT_TYPE_HEADER_NAME)) {