iet-ou/CR13/json-file : #13 Fix to safely get the contents of a URL as JSON [LACE] …

Hi Martin,
Please can you pull these various commits to fix issues relating to LACE (learning analytics), and generally increase flexibility and robustness.

Thanks,

Nick

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* Fixes this visualization, etc.: http://evidence.laceproject.eu/?page_id=155# ([OER Map equivalent](http://oermap.org/oer-evidence-map/))
* Related bugs: #8, #11(#10), #13, #14.