Make AWSJobStore work with us-east-1

[adamnovak]

As noted in boto/boto3#125, the AWS API has a long-standing bug where a bucket cannot be told to be in the us-east-1 region in the normal way.

Instead, when a bucket is to be placed in us-east-1, the whole CreateBucketConfiguration, which we unconditionally pass here, must be omitted.

As is, Toil lets you request that a job store be created in us-east-1, but will fail to create the bucket with:

botocore.exceptions.ClientError: An error occurred (InvalidLocationConstraint) when calling the CreateBucket operation: The specified location-constraint is not valid

We could also revisit whether having manually specified locations for buckets makes sense anymore; I think that since the system was designed, S3 was more or less globalized.

┆Issue is synchronized with this Jira Task
┆Issue Number: TOIL-957