Two base templates (for edit/create and display) created for node's common fields

1. New templates created:
   - templates/node_edit_base.html
   - templates/node_details_base.html
   - templates/drawer_widget.html  // Especially for prior_node and collection part

NOTE: You need to extend these templates whenever you need to create/edit and display templates for say, Image/Video as in image_create.html, image_edit.html, image_details.html

2. Templates renamed:
    - page.html to page_list.html

3. Templatetags modified:
    - edit_drawer_widget() added

4. methods.py modified:
    - get_drawers() function added

5. uls & views modified (page.py)