Correct test for selected

`is not False` throws `jinja2.exceptions.TemplateAssertionError: no test named 'False'`.

See docs for [lower-case `false` literal](http://jinja.pocoo.org/docs/templates/#literals) and [`sameas` test](http://jinja.pocoo.org/docs/templates/#sameas).
Merge pull request #18 from Yajo/patch-1

Correct test for selected