Extension template loader implemented.
admin/dashboard.html broken into:
   - admin/dashboard.html
   - admin/dashboard/dashboard_manage.html
   - admin/dashboard/dashboard_news.html
   - admin/dashboard/dashboard_server_info.html

for easier extension.

Manual:
   - created a dashboard_extension.html with no {% extends ...%} -> correctly loads the blank page in place of the dashboard
   - created a dashboard_extension.html with {% extends ...%} -> correctly extends the original dashboard
   - created a dashboard_manage_extension.html with no {% extends ...%} (both with and without the dashboard_extension.html) correctly displays all of the dashboard excluding the dashboard_manage.html
   - created a dashboard_manage_extension.html with {% extends ...%} (both with and without the dashboard_extension.html) correctly displays the original dashboard with the manage extension