Support sendMessage (and similar methods) accepting Arrays joined by newline

[ghost]

I know it's a fairly simple thing...but I've become accustom to sending Arrays of messages, and it would be handy if the lib would accept them as an Array. Helps clean up the codes a bit. =)

[briantanner]

This is a very small detail, but I have to say that I became accustomed to this as well, and I'm still catching the odd error where I forgot to .join('\n') lol