Fix compatibility with jQuery 1.9+

$.browser is gone there, but still we have to disable cache for MSIE.

COUCHDB-1668
diff --git a/jquery.couch.js b/jquery.couch.js
index b7e36f9..db4e8ef 100644
--- a/jquery.couch.js
+++ b/jquery.couch.js
@@ -977,7 +977,7 @@
     errorMessage = errorMessage || "Unknown error";
     timeStart = (new Date()).getTime();
     $.ajax($.extend($.extend({
-      type: "GET", dataType: "json", cache : !$.browser.msie,
+      type: "GET", dataType: "json", cache : maybeUseCache(),
       beforeSend: function(xhr){
         if(ajaxOptions && ajaxOptions.headers){
           for (var header in ajaxOptions.headers){
@@ -1058,4 +1058,17 @@
     return obj !== null ? JSON.stringify(obj) : null;
   }
 
+  /**
+   * @private
+   */
+  function maybeUseCache() {
+    if (!navigator){
+      return true;
+    }
+    else if (/(MSIE|Trident)/.test(navigator.userAgent)){
+      return false;
+    }
+    return true;
+  }
+
 })(jQuery);