Make resultspec searches more efficient

[johndgiese]

Currently result files are stored in big pickeled blobs; the pickled blobs can be quite big, depending on how much information is put into the "context" in the HDAT suite.

Because the pickle files are so big, and because we need to unpick each file in order to resolve a resultspec, resolving result specs can be quite slow.

It would be nice if we could resolve result specs only using the filesnames... this would probably be a lot faster.