mkdir creates bucket, and/or an empty object with a "/" suffix

mkdir now mimics the original functionality
- raises warning if bucket already exists
- uses the flags passed to it to be able to safely use @mkdir()

ignore atlassian plugin file

mkdir creates bucket, and/or an empty object with a "/" suffix

test trash removed
- a bit cleaner suffixing
- do not return true, if createDir() got only a bucket, and that one already existed
Merge branch 'master' of github.com:aws/aws-sdk-php
Merge remote-tracking branch 'miklos-martin/master' into stream_wrapper_mkdir
Updating S3 stream wrapper to support console style sub-folders.

- Moving creating buckets and pseudo folders to different methods.
- Making mkdir checks more explicit by checking (vs using is_dir).
- Fixing tests and adding an integration test for mkdir() with a key.