Implement Templates admin page

Create `templates` table in database
Add navigation links to Template page
Let admin to manage his templates from adminpanel
Make Smarty search template in database first

If not, fallback to file template
Implement normalizer to convert gettingstarted/../support/default.tpl to support/default.tpl
Add disable_template_override variable to Smarty

To disable Database Template Overriding and use original files
Show templates tree on Admin Templates page

Show active and activated templates in Tree
Make templates tree persistent
Merge pull request #867 from Kukunin/next

Admin Template Editor page