Remove Firefox from CI as it is problematic
Remove Firefox from CI as it is problematic

EWhite613/ember-frost-core,helrac/ember-frost-core,rox163/ember-frost-core,ciena-frost/ember-frost-core,ciena-frost/ember-frost-core,EWhite613/ember-frost-core,EWhite613/ember-frost-core,dafortin/ember-frost-core,dafortin/ember-frost-core,helrac/ember-frost-core,dafortin/ember-frost-core,rox163/ember-frost-core,rox163/ember-frost-core,ciena-frost/ember-frost-core,helrac/ember-frost-core