Ember.js JSHint not ignoring bower_components files

I'm building an Ember application which uses Bootstrap, and oftentimes it takes a very long time to build. I think (but am not positive) that this is because JSHint goes through my bower_components and finds errors like this:

The errors are all in bower_components/tether, bootstrap, or jquery. I have looked into excluding bower_components in .jshintrc but I haven't had any success with it.