update emr.sh to copy rain.txt into our bucket.

In running the examples on amazon's elastic mapreduce using the emr.sh script in the repo, I noticed that the data file used in part1 and part2, "rain.txt", isn't copied up to S3. this causes the job to fail.

I've updated the script to put the file on s3 before running the job, and tested by changing the bucket name to one that I own, and running the job.