add '.json' if Backbone.ajax used utils.ajax
Add Header['Accept'] if using utils.ajax
Revert "Add Header['Accept'] if using utils.ajax"

This reverts commit 769f36b56210b27b877f1c102d3b2bc7cbcb3434.
Add Header['Accept'] if using utils.ajax
Merge pull request #68 from hiphapis/master

add '.json' if Backbone.ajax used utils.ajax