jaques smith <> in Sakai.Git

KNL-1268 - Extract content file operations to support multiple backends

Thanks to OpenCollab ZA for the patch.

This makes way for filesystems other than local (or mapped) disk, such

as OpenStack Swift.

A new interface is added, FileSystemHandler, along with extracting the

default file implementation. I made a few fixes to update the patch and

clean up a few stylistic things to fit into the kernel code better, but

there are no name or design changes.