add clearMemory() method in Local Memory. Able to pass all tests in LogicTest.
implement sortByLabels(). Passed test 1 for sortByLabels().
Merge branch 'master' of https://github.com/cs2103aug2014-w09-1j/main
Merge branch 'master' of https://github.com/cs2103aug2014-w09-1j/main

Conflicts:
	src/mytasks/logic/LogicTest.java
	src/mytasks/parser/MyTasksParser.java
Resolve conflicts