Ddp pre1 emgee3

So I finally got around to working on pre1 support for the DDP client. I added the 'added' 'removed' 'changed' and 'ready' commands.

It's definitely not fully pre1 compliant. There's no EJSON support, 'error', 'addedBefore' or 'movedBefore', though the last two aren't actually implemented in Meteor yet. 

I'm not sure if you want to merge this or not, seeing how it is incomplete, but it's more complete than the previous 2 pull requests and both subscriptions and methods work. I've been meaning up update to the latest version of Meteor, but needed the DDP client update first.