Update S3FileObject.java

Implement doListChildrenResolved(). This dramatically boosts browsing/navigational speed by leveraging the information in the summaries to return attached FileObjects instead of Strings, thus eliminating at least one round trip per child object if you actually want to do something useful with the children.
Update S3FileObject.java

Removed half-implemented version of doRename() and implemented canRenameTo() to always return false.
Added implementation of copyFrom that lets copies within S3 be handled on the S3 side instead of doing a download and upload.
Update S3ProviderTest.java

Added copyInsideBucket() testcase.