Modified code to overcome Ctrl+Click issue in web-kit Browser like Chrome.

Following changes are done : 

 - ```base.html``` - Redundant call to jquery.js commented. Because as it's already included in base.html for foundation, which is recent version of jquery. And if any one observe commented jquery.js was old and request for ```jquery.min.map``` in Chrome.

- ```ajax_views.py``` - Using ```StreamingHttpResponse``` instead of ```HttpResponse``` to send graph json data. As it is recommended by Django (for v1.5 onwards).

- ```node_graph.html``` - $.getJson() was giving parsing error in chrome. Which is replaced with $.ajax()