test_bucket_create_exists should fail on recreate

AWS S3 has two behaviors for recreating a bucket depending if you use
the us-standard or another region:

```
>>> bucket = conn.create_bucket('gaul-default', location=Location.DEFAULT)
>>> bucket = conn.create_bucket('gaul-default', location=Location.DEFAULT)
>>> bucket = conn.create_bucket('gaul-uswest', location=Location.USWest)
>>> bucket = conn.create_bucket('gaul-uswest', location=Location.USWest)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/dist-packages/boto/s3/connection.py", line 499, in create_bucket
    response.status, response.reason, body)
boto.exception.S3CreateError: S3CreateError: 409 Conflict
<?xml version="1.0" encoding="UTF-8"?>
<Error><Code>BucketAlreadyOwnedByYou</Code><Message>Your previous request to create the named bucket succeeded and you already own it.</Message><BucketName>gaul-uswest</BucketName><RequestId>24B6DC3170365CD7</RequestId><HostId>hUynMTyqc9WZFxAJ2RFK6P7BqmmeHHlMl9xL2NOy56xBUnOZCAlHqGvtMeGeAfVs</HostId></Error>
```

Additional discussion:

https://issues.apache.org/jira/browse/JCLOUDS-334