Add validation for changing the status of a task

If the task is moved to a different status, the "Save" and "Clear" buttons are
now available.

Change-Id: I8bbd3f1003b8e490c9979f3f7816ca026285c3d1
Merge "Add validation for changing the status of a task" into dev
Merge branch 'dev' into feature/gui2

Conflicts:
	TaskManager/src/main/java/edu/wpi/cs/wpisuitetng/modules/taskmanager/presenter/TaskPresenter.java