traincam

This fixes https://github.com/openai/gpt-2/issues/26

```  File "C:\Users\James Pollack\Desktop\gpt-2\src\encoder.py", line 112, in get_encoder
    bpe_data = f.read()
  File "C:\Anaconda\envs\gpt-2\lib\encodings\cp1252.py", line 23, in decode
    return codecs.charmap_decode(input,self.errors,decoding_table)[0]
UnicodeDecodeError: 'charmap' codec can't decode byte 0x81 in position 66951: character maps to <undefined>```