Updated Meteor once more.
Initial version of support for references in MongoDB.
Started using PeerDB library.
Defined references.
Updated to newer version of PeerDB. Migrated everything.
Added comment.
It is better to reference documents instead collection.

It can allow us to possibly do smarter things in the future. We can
always get collection from a document, but getting a document from
collection is not really possible.
Merge pull request #152 from peerlibrary/mongo-references

Mongo references
Documented `esprima` issues. Fixes #153
Merge branch 'master' into new-annotations2