Fix bug #666

https://github.com/radare/radare2/issues/666

1. Wrong print message.
2. If number of section equal to 0, it does not mean that we can not load file. Correpond to this - https://code.google.com/p/corkami/wiki/PE (required elements, a more extreme PE can rely on even less elements:).

All another may be load without any section correspond to above link.