Fix Dancer::Test to simplify Dancer::Plugin and Dancer app test

Dancer1 and Dancer2 take params from hash.

Dancer1 take 'appdir' as an option.
Dancer2 take 'apps' as an option.

For a plugin compatible with Dancer1 and Dancer2 with can just do this :

use Dancer::Test appdir => '..', apps => ['MyApp1','MyApp2'];

so both will work fine.