CommandBox F2 has been deactivated

F2 key on CommandBox has been deactivated
TaskNote is added to Detail Panel

TaskNote is added to detail Panel
TaskType and TaskNote is added to writing to file

TaskType and Note has been added to writing
write categories to file

Write category list to file is done
Help Content is updated

Help Content is updated
TestCase for CommandStack has been added

TestCases for commandStack added
Merge pull request #75 from cs2103aug2014-t17-1j/Jack_UI

Jack ui