Support for a post_run script

[clburlison]

The main idea behind this is to have the location.plist uploaded to an externally available logging system. I have the skeleton code for uploading to AWS s3 finished.

• Handle errors gracefully. Though we should exit 0 when the post_run script works.
• Add a 10 second time out. If your upload takes longer than 10 seconds you're doing something wrong.
• Not sure if we should add a pre_run script however I'm open to ideas.
• Add tinys3_upload_example.py