Delete file from S3 fails because of missing normalization

Thumbor report successful delete while in practice the delete fails.

Branch Master Also release 6.2.12

Copy/paste the result of the pip freeze command here. We'll be most interested in the versions of 

boto==2.49.0
boto3==1.11.6
botocore==1.14.6
thumbor==6.7.0
tornado==5.1.1
tornado-botocore==1.5.0
tornado-pyvows==0.6.1

### Configuration
TC_AWS_STORAGE_BUCKET = 'vo-thumbor-bucket' # S3 bucket for Storage
TC_AWS_STORAGE_ROOT_PATH = 'testDeleteImage' # S3 path prefix for Storage bucket
TC_AWS_REGION = 'us-east-1'

### Steps to reproduce

curl -i -H "Content-Type: image/png" -H "Slug: test.png" -XPOST http://localhost:8080/image --data-binary "@Avatar-85-256.png"

curl -i -XDELETE http://localhost:8080/image/1e98c320dd714290a33403e5c8e75b86/test.png

Delete is returning 204 but the file is not deleted in S3    :(

[eitanshapiro]

Adding this code to s3_storage.py solves the issue

@return_future def remove(self, path, callback=None): “”" Deletes data at path :param string path: Path to delete “”" super(Storage, self).remove(self._normalize_path(path), callback)

[Bladrak]

Duplicate of #144