Step 1: Added angular directives

Added ng-app, ng-controller and ng-repeat to list the plants defined in
the PlantListController. Also added a test to verify the controller
code.
Step 2: Added a Search query box

The app now has a search box. The plant list on the page changes
depending on what a user types into the search box.
Step 3: Added end to end test using protractor
Step 4: Added a dropdown menu to sort the items