crude hack to get ack callback on with socketio 1.0
fixed packet encoding to keep backward compatibility with 0.9
updated readme
cleaner fix for ack 0.9 and 1.0 cb
fix when ack number more than 1 digit

fix when ack number more than 1 digit
Merge pull request #1 from hearther/master

fix when ack number more than 1 digit
Merge pull request #1 from francoisp/master

ack callback on with socketio 1.0