Prefixed tracker version with "js-" (snowplow#188)

Author: fblundun

src/js/snowplow.js

@@ -89,7 +89,7 @@
 			windowAlias = window,
 
 			/* Tracker identifier with version */
-			version = '<%= pkg.version %>', // Update banner.js too
+			version = 'js-' + '<%= pkg.version %>', // Update banner.js too
 
 			/* Contains three variables that are shared with tracker.js and must be passed by reference */
 			mutSnowplowState = {