Merge Space staging path and SS internal location
It is confusing for each Space to have a staging path, as well as a storage service internal location.
The original reason was to have a staging path that was on the target space, but was locally accessible. With spaces like Swift and Duracloud this is less relevant, and the extra paths are confusing.
Probable solution is to remove the SS internal path completely, and replaces all uses with move to/from the SS internal location.