Comments for class
Added documentation
Added some variables to simplify code
Changed getControllerInstance to getInstance
Changed executeCommand() access modifier for testing

Changed from private to package private.
Merge branch 'controller/sharon'
Prepared Controller for unit test

Created a protected constructor for unit testing which is conducted within
the package.
Added Sync and Exit command types, along with some unit test cases
Added Search command

#42
Prepared Logic for dependency injection

Added Logic constructor for extension.
Created LogicStub class which extends Logic.
Merge branch 'controller/sharon'
Included input validations for search, sync and exit

#42 #43
Created unit test for Controller
Merge remote-tracking branch 'origin/parser/Victor'
Merge branch 'master' of github.com:cs2103aug2014-w10-3j/main into db/sean
Created unit test for Controller
Use lower cases for key
Actually create the hashmap
Use the lowercase representation of the string to find the key
Cannot use exceptions to throw too many things around