Added JSInput template to Studio and a sop attribute to JSInput. Only if it's set to false, as in JSInput's template, will JSChannel be used to bypass it. In all other cases (attribute not present or set to something else), SOP is enforced. Compatibility with jsVGL is therefore maintained. Multiple JSInput are supported in a vertical. Also, save button now functions. [BLD-523, BLD-556, BLD-568]
Merge pull request #1796 from edx/jmclaus/feature_jsinput_template

Added JSInput template in Studio.