Hello World program for NNN50 SoftAP mode

Dependencies:   NNN50_WIFI_API

This is a SoftAP example for Delta DFCM-NNN50 platform. In order to test with this example, user first need to open TCP Client port (use port 1030 in this example) on a PC or mobile with Socket test tool (download RealTerm' for PC, and Socket X for iOS or anymore socket test tool program available) When this example is running, the module will run as SoftAP with TCP Server. A PC or mobile can then connect to the SoftAP and connect to Server port. Once Server port is connected, user can send out the test message and expected to receive the reversed test message reply by Delta DFCM-NNN50. For more information on the usage of regular TCP and UDP Sockets, the mbed handbook can be found here