Add demo S3 access and secret key for the test account to README

[diwu1989]

We had to use the swift client to get the s3 access and secret key.
Can we just bake in the S3 access and secret key into this image and provide the key in the README?

[timuralp]

@diwu1989 I'm not sure what you mean by "use the swift client to get the s3 access and secret key".

The following configuration for s3cmd works for me with the container:

[default]
access_key=test:tester
secret_key=testing
host_base=localhost:32768
host_bucket=localhost:32768
use_https = False

Afterward, I can execute the following:

$ s3cmd ls
$ s3cmd mb s3://foo
Bucket 's3://foo/' created
$ s3cmd ls
2009-02-03 16:45  s3://foo
$ swift -A http://localhost:32768/auth/v1.0 -U test:tester -K testing list
foo

Do you observe different behavior? Are you trying to use a different account or different credentials?