Make Doo work with Karma 6.x

[miikka]

The Karma command is supposed to be karma start <config file>. However, Doo has been generating karma start <config file> <path to js>. As far as I can tell, before version 6.0.0, Karma used to ignore the extra argument. Since version 6.0.0, it gives an error message and exits.

This change drops the extra argument for Karma, which seems to fix the problem.

[miikka]

It seems that CircleCI integration has, once again, broken. Ah well.