test fixes for temporary file handling

$q->param( POSTDATA ) now returns the blessed filehandle:

	bless( \*{'File::Temp::$fh'}, 'CGI::File::Temp' )

which doesn't always seem to pass the ok test in Test::More so turn
that test into a isa_ok and check the returned object is all types:
File::Temp, CGI::File::Temp, Fh so all compatibility layers documented
are available