Updated system test for create using description

--description, -desc, --information, -info, -a
System test for create using time

--time, -t
System test for create using deadline

--deadline, -d
Used parser
Merge branch 'controller/sharon'
Refactored method feedbackForShow to feedbackForRetrieve
Improved look of show command
 - Will now say it is showing all or, the specific task number.
 - Added details of task when showing only one task.

#48
Added output for Search

#55
Added more details to feedback message for add

#57
Added more details to feedback message for update

#57
Added systest for retrieve
Updated systest for retrieve, added for update
Updated update, added delete

Delete check corner case first and last index
Made parser instance class private, refactored showWelcomeMessage()
Activated exit command

System.exit(0);
Added comments, adjusted some methods for reusability

Comments for controller constructor with stub parameter.
Deleted showWelcomeMessage() method, but adjusted processString() to be reusable for system generated and user keyed commands.
Refactored terminate(), added comments

Shows exit message and exits system.
Merge branch 'master' into logic/wenhao
Merge remote-tracking branch 'origin/controller/sharon' into logic/wenhao
Merge remote-tracking branch 'origin/parser/Victor' into logic/wenhao
Fix Issue #61 Issue #59