Fix UltraISO Exploit File Creation

Both ultraiso_ccd.rb and ultraiso_cue.rb use File.open to create
files, instead of using the create_file() function. This leads
to files being created in the wrong directory.

We work around this by dynamically changing the
file_format_filename function to return the corrected filename.
Fix UltraISO file creation

This makes file creation where datastore['FILENAME'] is not used when
a different filename is required, and ends up creating files in the
wrong place.
Land #1934 - Fix UltraISO Exploit File Creation