Decouple tests from unspecified data ordering

These tests have been passing with SQLite, but don't reflect guaranteed
behavior and with PostgreSQL failed intermittently.

spec/controllers/api/v1/tracks_controller_spec.rb

@@ -16,9 +16,7 @@ describe Api::V1::TracksController do
 
         expect(response).to be_success
 
-        expect(json.length).to eq(2)
-        expect(json[0]['name']).to eq('Conference Track')
-        expect(json[1]['name']).to eq('Test Track')
+        expect(json.map { |t| t['name'] }).to contain_exactly('Conference Track', 'Test Track')
       end
     end