GreaterThanTest works

My design works for the GreaterThan and EqualSearch!! What I did is
creating Custom search class in Node.java file, just like SearchField
class for EqualSearch, and let all the Custom searches extend from
Traverser abstract class, but have their unique process() methods. We
also have different classes for searches, like GreatThanSearch, which
extends from Search (an abstract class), and override its doSearch
method. Inside doSearch methods, create their own new object of
Traverser and call D.fetch(Traverser t) to let it perform different
kinds of search functions
Merge branch 'master' of https://github.com/maryfeng/FinalSearchEngine

Conflicts:
	org/uiowa/cs2820/engine/FieldSearch.java