Work around BucketAlreadyOwnedByYou

Buckets outside of the standard region will raise an error if you try
create them and they already exist. See:
https://forums.aws.amazon.com/thread.jspa?threadID=119095
Merge pull request #25 from andrewsnowden/reuse-existing

Fix BucketAlreadyOwnedByYou on non default S3 regions
Merge branch 'master' of github.com:e-dard/flask-s3

Conflicts:
	flask_s3.py