Bug resolved in displaying div's on click of tab elements.

* As issue reported and assigned regarding back key on the browser to go back to file from edit mode, 
Modified ```node_edit_base.html``` template, removed the unecessary click events which are triggered when edit page loads. 

* The problem was due to "href" attribute which is used on click of every tab, when user clicks on any of the tab, that tab was used to activate the div panel for showing the contents. But , as we know, all tabs are based on ajax calls ,to remove unecessary loading of contents, hence "href" and "ajax call" was placed on the same tab" because of which browse was unable to keep the track of events occured on page. 

* Now bug resolved, removed the "href" attribute which was conflicting, and also written jquery for activating div's and displaying contents.