Fixed errors with new versions of Dancer2

I have added the ":no_dsl" flag for Dancer2::Plugin and removed the call for plugin_setting because it was returning and error(Exception caught in 'core.app.before_request' filter: Hook error: Can't locate object method "dancer_app" via package "Dancer2::Plugin::Deferred" at /home/evodev/perl5/perlbrew/perls/perl-5.18.2/lib/site_perl/5.18.2/Dancer2/Plugin.pm line 123.)