fixed deps discrepancy in unwind, exposed DepsTracker

lib/pipeline/documentSources/UnwindDocumentSource.js

@@ -112,7 +112,7 @@ proto.getNext = function getNext(callback) {
 	var self = this,
 		out,
 		exhausted = false;
-		
+
 	try {
 		out = this._unwinder.getNext();
 	} catch (ex) {
@@ -190,7 +190,7 @@ proto.getDependencies = function getDependencies(deps) {
 		throw new Error('unwind path does not exist!');
 	}
 
-	deps[this._unwindPath.getPath(false)] = 1;
+	deps.fields[this._unwindPath.getPath(false)] = 1;
 
 	return DocumentSource.GetDepsReturn.SEE_NEXT;
 };

lib/pipeline/index.js

@@ -2,6 +2,7 @@
 module.exports = {
 	Pipeline: require("./Pipeline"),
 	PipelineD: require("./PipelineD"),
+	DepsTracker: require("./DepsTracker"),
 	FieldPath: require("./FieldPath"),
 	Document: require("./Document"),
 	Value: require("./Value"),