Adding qunit.css to tasks folder, altering .gitignore for intellij files

Adding the qunit.css file to the tasks folder so that we can use the node_modules version of qunit to run our tests via the browser. Should help to reduce issues where the tests pass in the browser but fail in the console due to version mismatch. (New to grunt plugins, let me know if this doesn't work at all. I would love to learn some more)