Date format for date picker in JS is not configurable

The javascript for the dashboard currently has the date format for the date picker hardcoded in [dashboard.js line 17](https://github.com/tangentlabs/django-oscar/blob/master/oscar/static/oscar/js/oscar/dashboard.js#L17). This might conflict with the date format specified for a date field of a form (which happened in fancypages).

My suggestion would be to make the date format configurable in some way. I am not sure what the best way would be to handle this and potentially keep it in sync with the format specified in the settings file. There are two ways I can think of right now:

1) Use ``django-compressor`` and run the JS file through the TemplateFilter which would allow us to generate the date format whenever the JS file is generated.

2) Pull the format dynamically into JS. I am not sure if there's an option other than an API call to the backend. But this seems a bit over the top to me. 

Any thoughts on this? Is this something we should consider or is the hardcoded format fine for now? Any ideas how to make it configurable if we decide to do so?