Google calendar: Added support for "Private Address" URL without authent...

Added support for using "Private Address" without authentification by username/password.
The following cases should be supported:
1) URL, username, password
2) private-URL

To obtain the private URL:
- login in to https://www.google.com/calendar/
- click "Settings" (under "My calendars") -> <your calendar> -> Private Address "XML"
- copy the given url and replace "basic" with "full" 

The address should be on form:
https://www.google.com/calendar/feeds/jo@gmail.com/private-08ce2fac8efa42f2a0d04eceb7d68cc9/full
and no username/password