Uses Undoable interface to distinguish Command objects that are undoable
Cleans up unused imports in unit tests
Displayer assertion added

 to  check parameter not null
Create LoggerUI to log for UI class
Log "UI created" for creation of UI Screen
Log "Exit Dynamiz"
Update logger when command "exit" is entered
Log for each display method in UI
Assert for UI completed (collab with Nhan)
Merge branch 'master' of https://github.com/cs2103aug2014-w13-2j/main.git
Adds CommandDo class
Merge branch 'master' of https://github.com/cs2103aug2014-w13-2j/main
Displayer html tag added
Merge branch 'master' of https://github.com/cs2103aug2014-w13-2j/main
DisplayFormmater name refractor
DisplayFormmater updated
Changes CommandSearch's constructor
Completes search by various data members of ToDoItem subclasses
Updates CommandSearch documentation and runs unit test for CommandSearch
DisplayFormatter attach HTML TAG