Fix for #12; removed copyFrom(..) and doCopy(..) in S3FileObject since
they didn't appear to create intermediate folders correctly in S3 (the
folders cannot be subsequently deleted); instead, all put operations now
use the S3OutputStream class, via FileUtil.copyContent(..) and
S3FileObject.doGetOutputStream(..); internally, S3OutputStream now uses
the TransferManager, and sets content length and content type metadata