Bump sentry_version to 3

No idea what this does, but @Zeeg said to do it.

Author: mattrobenolt

src/raven.js

@@ -307,7 +307,7 @@ function getAuthQueryString() {
     if (cachedAuth) return cachedAuth;
 
     var qs = [
-        'sentry_version=2.0',
+        'sentry_version=3',
         'sentry_client=raven-js/' + Raven.VERSION
     ];
     if (globalKey) {