improve GUI
label invisibility yes
change font and fix invisible border, hi light prob
Merge branch 'Ben's_branch' into linh-dev

Conflicts:
	src/todologApp/UserInterface.java
add popup functions and change exit/show/hide functions
add DBStorageStub
put in the comments and got rid of the useless code
Merge branch 'Ben's_branch' into linh-dev

Conflicts:
	src/todologApp/UserInterface.java
refactor UI, remove some unused imports
Merge branch 'linh-dev' of https://github.com/cs2103aug2014-t11-3j/main into Stanley's_Branch