Cross Platform compatibility

[dakies]

red_pitaya_streaming_client_python/rp_stream_threaded.py

Line 138 in 05c07eb

[header,index,lostrate,oscrate,buffsize,ch1_size,ch2_size,resolution]=struct.unpack('16sQQLLLLL',bytes_data[0:52])

In order for the code to work on my mac, I had to change the format string to '=16sQQLLLLL'