allow rmdir to remove bucket or object
fix rmdir tests
check if any objects exist in s3 pseudo-bucket before remove it
Added support for credential files and credential profiles
Merge pull request #270 from aws/credential-files

Added support for credential files and credential profiles
Update README.md
typo

ocd? :>
Merge pull request #272 from pmoust/patch-1

typo
Merge pull request #271 from GrahamCampbell/read

Update README.md
Merge remote-tracking branch 'alexk/rmdir-fix'
Fixin up deleting pseudo directories

- Adding a trailing "/" if needed so that it is not required.
- Restructuring the logic to be a bit simpler.
- Adding a test to ensure that "/" is not needed.
Better handling flags in stream wrapper errors

PHP stream wrappers provide flags to url_stat that should be used to determine
the response of a call and whether or not it raises an error. I've updated the
Amazon S3 stream wrapper to utilize these combinations of flags to emulate the
error handling of the "http" protocol stream wrapper.

Closes #268
Merge pull request #276 from aws/fix_is_link

Better handling of error flags in S3 stream wrapper
Added additional logic to DynamoDB WriteRequestBatch abstraction.

The situation where an entire BatchWrite operation is throttled due to exceeding the provisioned throughput is now handled.
Updated some links in the docs and README
Small update to credential logic for more robustness
Updates to docs to talk about credential files and the profile option.
Removing a specific usage pattern for iterators and waiters from the docs in order to discourage it.
Updated OpsWorks model.
Updated EC2 model and added R3 instance types.