Provided QuestionNode class and testing case that holds the functionality for the question nodes in the question tree
Updated formatting on QuestionNode.java
Added interface that is able to encapsulate writing QuestionTree
Provded QuestoinNodeFileWriter class and testing case, including mock object to test functionality.
Updated QuestionNodeWriter interface to cover new class
Updated interface for QuestionNodeWriter to TreeWriter to better describe its functionality. Altered concrete class and test case accordingly
Updated PrintStreamMock with copy of GPLv2
Provided TreeBuilder interface, which will provide the inverse operation of TreeWriter.
Added GPLv2 to the missing interfaces respectively