Added Search within date period

add search within date period with accompanying test
update_logic
Merge branch 'master' of https://github.com/cs2103aug2014-w11-4j/main into update_logic

Conflicts:
	src/Logic.java
delete_Task tests added
delete_Update tests added
Merge branch 'update_logic'

Conflicts:
	src/Command.java
	src/Logic.java
	src/MenuInterface.java
	src/Parser.java
	test/LogicTest.java