MDL-27542 calendar export: fixed the following:

1. changing auth token to use user id instead of username
2. add fall back checking for old url
3. remove yui functionality to generate calendar url
4. add missing variable
5. fixed usercontext instance

lang/en/calendar.php

@@ -28,6 +28,7 @@ $string['allday'] = 'All day';
 $string['calendar'] = 'Calendar';
 $string['calendarheading'] = '{$a} Calendar';
 $string['calendarpreferences'] = 'Calendar preferences';
+$string['calendarurl'] = 'Calendar URL: {$a}';
 $string['clickhide'] = 'click to hide';
 $string['clickshow'] = 'click to show';
 $string['commontasks'] = 'Options';