add say module

Usage: say message
Little bug: the bot crashes if you have a question mark in the message.
I guess this could be done a lot easier. Also, to fix that bug, we could do:
wStream = fs.createWriteStream("./modules/say/" + user + ".txt", {flags: 'a'}); instead of
wStream = fs.createWriteStream("./modules/say/" + message + ".txt", {flags: 'a'});