Curl option CURLOPT_HTTPAUTH inserted

Set curl option CURLOPT_HTTPAUTH, if the url includes user name and password.
e.g. http://username:password@www.example.com/cal.ics
Remove unneeded code

The removed code is unneeded because the variable $isFile cannot be true at this position. See line 74.
Merge pull request #32 from bitschubse/master

Some changes on iCalImport.php