Collection navigation module implemented

## Features implemented ##

* Now from each node's collection we can easily navigate from all its inner hierarchy without reloading the entire page.

* Since from this collection navigation module, we can get easy idea of each node's hierarchy level, at the same time it doesnt loose the context while navigating from collection hierarchy, hence we dont require to show the breadcrumbs to acheive this feature. User can always used to see from where he/she came from with its inner/outer hierarchy level on left side panel. 

* Also on click of each collection node browser url also changes accordingly without reloading page.
Used  ```window.history.pushState()``` method, to display the clicked node's url based on the node type.

* Currently, we are not showing the image thumbnails or video thumbnails in collection module, since there is not much enough space to show those thumbnails, we should keep this module as lightweight as possible so that it will not take much time to load the collection hierarchy. 

* Bug resolved in begin discussion link, after navigated to any of the node's collection ,discussion feature can be used. Onclick event is now placed on Begin Discussion link which enables us to start the discussion after navigated from collection hierarchy.

* Bug resolved in displaying relation node's of a node, used get_neighbourhood() while accessing each node from its collection hierarchy.

* Also "Draft" text is now displayed beside the name of the node till its not published, since it attracts the users attension about the status of the node , as this change was suggested previously.

* Regarding saving the node as a collection , its criteria to save according to its hierarchy level such feature will implement it soon.

* Removed ajax loader image which always use to display on the center of the page.

## What is to test ##

* check if collection hierarchy works properly.