Update for API changes in placard.
Remove unused imports.
Fix depreciated module reference.
Fix depreciated module reference.
Improved support for django 1.5
Fix URLs.
Change the quote characters, it breaks the upgrade_template command.

Yes, this is a hack. The upgrade_template parses the file as HTML,
and doesn't understand nested quotes inside Django template entries.
Update all templates with upgrade_template.
Prepare to release 2.7.0
Fix lintian warnings.