Removal of json2.js

    As long as Horizon does not support any browser lower than IE8,
json2.js library is no longer needed, browsers have a native
implementation of JSON.stringify and JSON.parse.
    Removing this script allow us to reduce the javascript footprint
of Horizon.
    jQuery $.parseJSON will replace all parsing of JSON in order to
standardize the use of this functionnality.

Change-Id: Ifaf027e2adc462ee7b3d9587b28583ade376ccfc
Merge "Removal of json2.js"