Tidied up the todo controller, moving the first utility function to the Angular service
App: Created a utility function in the Angular service for creating navigation bar buttons, and used that in the list controller
App: Created a web view manager in the Angular service and updated all view references in the code
Updated the "load todo list" event listener to only retrieve the list if on the todo list page. Previously this request was being made every time a new page was loaded, slowing down the application with unnecessary requests.
App: Updated the icons on the view single todo page to more meaningful icons
Minor styling updates: Changed the app background colour to off-white to contract with the white background of the actual content. Tweaked the layout of the view todo page.