add exception handling

MismatchedCommandException in taskManager methods.
add priority to Task
improve test for Task
add logging to Controller
add .log files to gitignore
Merge branch 'master' into sun-defcoding
Defensive Coding
Exception and Logging implementation.
getTasks for UI
Add Controller.getTasks() so data will be populated in the ListView
Merge remote-tracking branch 'origin/tys-ui' into sun-defcoding

Conflicts:
	src/application/Controller.java
merged with SUN BRANCH Controller.GetTasks()
resolving conflict
Merge branch 'sun-defcoding' into tys-ui
Data will be initialize when the UI Loads
added a Controller.getTasks() which the UIComponent use as a flag to tell
the controller that the ListView are instantiated and ready to be
populated.
removal of temporary code for merging
updated the rectangle height based on the list cell height
Merge branch 'master' of https://github.com/cs2103aug2014-w14-2j/main into xjy-parser