Deprecate and recommend meteor-reactive-aggregate instead

[jedwards1211]

I was just searching for a reactive aggregation solution and found this: https://github.com/JcBernack/meteor-reactive-aggregate
It allows you to specify a Mongo query to observe for changes, which defaults to any changes in the collection. This way it can provide reactive aggregation.

[jedwards1211]

Whoa, I didn't really look but that package uses this one to call the aggregate method. Which it needn't necessarily do. But obviously there should be something about that package in the README for this given the number of issues asking about reactive aggregation.