setup Karma unit tests

so we can start writing some unit tests :)
mistake. I updated the angular generator and created a new grunt file.
I thought I included all our [changes](https://github.com/EverythingMe/redash/commits/72e41a94e471523bdb59e99e9e2249994b5d741a/rd_ui/Gruntfile.js)
are we missing anything else?