Renamed Zijie's File I/O class

The original name “ReadWriteFiles” does not comply with naming
convention.

additionally: added “.class” into .gitignore file.
Minor refac for FileHandler class
Renamed AddCommandInterpreter to Interpreter

To better reflect the newly design usage
Added Controller, moved main method here
added *.class in .gitignore
Renamed Display to DisplayData

To better reflect its functionality, reduce potential confusion caused
by vague naming
Correct spelling

change all 'discription' to 'description'
Renamed the GUI to UserView

To avoid confusion. Since UserView and Controller handle GUI stuff
together.
Merge branch 'Xuehe-for-V0.1-demo' of https://github.com/cs2103aug2014-t10-3j/TaskBar-WalkingSkeleton into Xuehe-for-V0.1-demo

Conflicts:
	bin/taskbar/GUI.class
	src/taskbar/GUI.java
Enforce camel case for get and setDescription()

Also deleted files that’s no longer useful in the new architecture.
Added update() to UserView.

This method is to be used whenever something new needs to be displayed
to the user.
Refactored Interpreter to be a function library

Refactored the interpretAdd() method to be static.
Implemented delete, complete, add, view
Implemented update() in controller.
Bug fix for update & complete
Deleted DeadlineTask and Event

Since all functionality now is included in the Task class.
Refactored interpretAddCommand() accordingly.
V0.1 Demo version completed

This version support basic functionality:
add\[description]\[label]\[importance]
view
delete [serial number]
complete [serial number]
update [serial number]

This commit also fixed a convertTaskToAddCommand bug.
Merge branch 'Xuehe-for-V0.1-demo'

Conflicts:
	src/taskbar/Storage.java
	src/taskbar/Task.java