[CHORE] Rollback the Karma dependency version
[CHORE] Rollback the Karma dependency version

`karma` was taking a long time (~30s) to exit the test suites
when it is run from `gulp`. There is an ongoing issue and the
temporary workaround is to keep the `karma` version at `1.3.7`.
https://github.com/karma-runner/karma/issues/1788

Dilatorily/packery-angular,Dilatorily/packery-angular