Error fix

[arturhood]

This code did not subscribe correctly to the "Messages" collection.

Fix recommended here: #10

[arturhood]

This is strange...
in this branch I changed "subscribe" to "$subscribe" to make it work, but in a similar case I'm getting errors until I change "$subscribe" to "subscribe".

The errors in the console were:
Error: You must provide either a function or an object with the update() method.
[Vue warn]: Error in created hook: "Error: You must provide either a function or an object with the update() method."