Implemented the plants details view.

when you click on a plant in the list, the plant details with the
plant-specific information is displayed. The $http service is used to
fetch the json file of the selected plant.
The mock $http service called $httpbackend is used in the unit test for
the controller to configure fake responses to server requests. These
features are provided to us by Jasmine and angular-mocks.js
Added a custom display filter

The custom filter converts the text strings true and false to glyphs.