fixing checksum by reading binary

# fixing checksum by reading binary

## test

this command return an error before this patch

	python3 smugline.py upload åäö --from=/c/file/txt/program/smugline/test --api-key='' --email='' --password=''

	  File "smugline.py", line 103, in _file_md5
		data = f.read(block_size)
	  File "/usr/lib/python3.2/codecs.py", line 300, in decode
		(result, consumed) = self._buffer_decode(data, self.errors, final)

	UnicodeDecodeError: 'utf-8' codec can't decode byte 0xff in position 0: invalid start byte