use assigns(:results) instead of @results in spec

I was able to make the tests pass by using `assigns(:results)` instead of `@results` in the spec for TermController:

```ruby
      it "should return a set of terms for a given query" do
        get :index, { :use_route => :lcsh_suggest, :q => "Blues" }
        expect(assigns(:results)).not_to be_nil
      end
```

I took the liberty of switching from `eval` to `JSON.parse` in the TermController itself.