OpenfMRI Dataset Descriptor using HCLS

This is an example implementation of the [HCLS Dataset Descriptor](http://htmlpreview.github.io/?https://github.com/joejimbo/HCLSDatasetDescriptions/blob/master/Overview.html#) for the OpenfMRI datasets.

This descriptor currently covers ds000001 and shows how an rdf distribution of a dataset can be split up into each of the NI-DM Components - Experiment, Preprocessing, and Results. The example also shows how rdf versions of NI-DM Components can be linked together using void:Linkets.

Also included is a python script that captures the *current* HCLS requirements for Summary, Version, and Distribution levels of description. 
@satra, as we discussed, xnat and the website use a six digit identifier, while the data directory uses the 3 digit + letter. ideally we would harmonize the aws and the website ids