Implemented config parameter for path style access - supersedes pull request #37

I've re-named the bucketInHostname parameter to pathStyleAccess. Since the first pull request I became aware that the s3 client options in the AWS java api have a parameter with this name and I wanted to make it consistent.

I've implemented some unit tests for the construction of urls using this parameter and to test that the defaults remain as they were. In the process I split the tests into config tests and bucket tests. This makes it easy to run the config tests without having to do all the config setup necessary for the bucket tests.

I re-based the original change onto the most recent master branch.