Django 1.5 support

**Put quotes around the first parameter of url template tags**

The first parameter do not allow unquoted string since Django 1.5.

**Add context_keys to TemplatesGenerator**

MODEL_NAME_archive_year.html uses 'year' the context of YearArchiveView.

But, on Django 1.5, it is returned as a date object.

So the template must use 'year.year'.

In order to maintain backward compatibility, add context_keys and set proper key depending on the version of Django.