incorrect browsers listed in karma config

the [browsers in the config file](https://github.com/jdhenke/celestrium/blob/747e2165feaac178111b87b4f53b6996fd8dba8c/karma.conf.js#L52-L60) are incorrect and misleading as they are actually being specified from the [command line](https://github.com/jdhenke/celestrium/blob/747e2165feaac178111b87b4f53b6996fd8dba8c/package.json#L6).

should probably put everything in the config file.