Use ajax helper function for _session GET request to stop request cache in IE7
diff --git a/jquery.couch.js b/jquery.couch.js
index 34255bb..3b49121 100644
--- a/jquery.couch.js
+++ b/jquery.couch.js
@@ -139,7 +139,7 @@
      */
     session: function(options) {
       options = options || {};
-      $.ajax({
+      ajax({
         type: "GET", url: this.urlPrefix + "/_session",
         beforeSend: function(xhr) {
             xhr.setRequestHeader('Accept', 'application/json');