Fix OC.filePath() call to let it add the proper 'index.php' in the URL.

OC.filePath()'s 'file' argument should not contain URL
parameters: the function checks if the requested filename
finishes with a '.php'.
Merge pull request #2 from otetard/bugfix/filepath

Fix OC.filePath() call to let it add the proper 'index.php' in the URL.