Added ability to send an empty contexts array (closes #296)

Author: fblundun

core/CHANGELOG

@@ -1,6 +1,7 @@
 Version 0.4.0 (2014-xx-xx)
 --------------------------
 Updated contexts schema to 1-0-1 (#292)
+Added ability to send an empty contexts array (#296)
 
 Version 0.3.0 (2014-11-04)
 --------------------------

core/lib/core.js

@@ -68,7 +68,7 @@ function trackerCore(base64, callback) {
 	 * @return object Outer JSON
 	 */
 	function completeContexts(contexts) {
-		if (contexts && contexts.length) {
+		if (contexts) {
 			return {
 				schema: 'iglu:com.snowplowanalytics.snowplow/contexts/jsonschema/1-0-1',
 				data: contexts