resolving conflict and continued work on undo
Merge branch 'master' of https://github.com/cs2103aug2014-w09-1j/main

Conflicts:
	src/mytasks/logic/LogicTest.java
Completed AddCommand and UndoCommand for add

minor addition to Command.java
adding a new method in LocalMemory.java
modifying the function calls in MyTasksLogic.java