Add'l checking for invalid bucket names

This is an interesting one. Dave Hill was starting to test the S3 functionality. Everything looked fine, but the connectivity test would fail with a cryptic SSL cert error msg from curl. It came down to his choice of bucket names. It had multiple periods, and this screwed up the SSL certificate verification.

Apparently this is a known problem. It makes sense when you think about the way the URL is constructed (bucket.s3.amazonaws.com). If the bucket has mulitple periods, it can obviously mess up the field breakout somewhere.

Even though AWS may not have a problem with a bucket named bucket1.2.3.4, we'll have to disallow that in the code.
1) Make SM log that this is an invalid bucket name
2) in the cmdline s3 options in postConfig, detect and reject