Fixes LP Bug #827660 - Swift driver fail 5G upload
    
    Fixes LP Bug #827660 - Swift driver fails to
    upload image files greater than 5GB. The swift
    store driver was not using the large object
    manifest methods required to upload objects
    greater than 5GB into Swift.
    
    Adds configuration options to specify the
    size in MB that an image file should be considered
    for large object manifest, and a configurable
    chunk size. We use a disk buffer of this size,
    adding chunks of the image file into Swift and
    then after all chunks are saved, add the manifest
    to Swift.
    
    Change-Id: I4b4421aa1bba584ab242016a041e864ef19d0214