Ensure all files are present in bulk import load mapping.

[keith-turner]

This is follow up work to #436. It would be nice to add a sanity check to the new bulk import code that ensures every file in the dir is represented in the load mapping file.

[keith-turner]

There are checks and test for the checks to ensure that the set of files in a load plan equals the set of files in the dir.

[ctubbsii]

@keith-turner Does your previous comment mean no work is done, or is necessary? If so, we should remove the 2.0 label.