Minor fix for problem with unterminated strings

1 - I fixed the problem with undetermined strings.

2 - I think it will be useful to have a random sample from the stream to use as a training dataset, so I've added a '-s' flag to the streaming.py program. This will make it listen to the firehose sample (1% of all tweets with no spatial filtering). I'm starting this on my office PC. Also made a shell script: streaming-firehose.sh. It assumes the 'firehose' directory exists (which needs to be ignored in gitignore file).