Performance Improvements


**Functionalities implemented:**

1) views/group.py

- RCS (versioning) implementation removed from Group 

  - While displaying group details, data is fetched direclty from database rather than from rcs-file.
  
2) templates/ndf/node_ajax_view.html

- Restriction on displaying widgets (Location, Graphs) on node details

  - These widgets are now going to be displayed only for GSystems (or instances) of Topic/Concept

- Tab (Changes) displaying *Versions* is commented out for time being

  - Causing performance issues: Making slower to load detail-view
  
  - TODO: This view should come on ajax call when a user clicks on that tab and code (version_dict) needs to be modified. 

3) templates/ndf/page_list.html

- '# Edits' removed from right-bottom of the card-view

  - Causing performance issues: Making slower to load card-view in list-view

4) templates/ndf/base.html

- Unnecessary call to temaplate-tag (get_gapps_menubar) removed.

5) templatetags/ndf_tags.py

- get_gapps_menubar(): This template tag deleted. (Not used anywhere)