Add loading of concatenated HDF jsons

[ejaronne]

Currently Heimdall doesn't know how to process more than one HDF result set within a file. Some users might concatenate a set of HDF files for a given environment including spanning different types of scans and mutiple scans over time.

Allow Heimdall to distinguish each properly and separate them out in Heimdall. 2-different-InSpec-jsons.json.txt 3-different-hdf-jsons.json.txt