Support for encodings other than UTF-8

Hello guys :)

As requested by #202 and #205, I have developed the support for encodings other than UTF-8. 

I added a command called /encoding [NEW-ENCODING] that should tell the Kiwi Server to expect that NEW-ENCODING from the IRC server. Kiwi server does the conversion using the iconv-lite library.

It still lacks of a GUI but it is fully functional. 

I tested with two encodings so far, one with my mother language, Brazilian portuguese using windows-1252:
![windows-1252](http://imageshack.us/a/img534/3075/n81u.png)

And I connected to a Russian server, so I could test the Cyrillic (windows-1251):
![windows-1251](http://imageshack.us/a/img837/3572/vn3q.png)

Seems to be working pretty well :)