Supporting classes for using aqueduct-sync with Meteor mongo database.

• buildQueue(db, collectionName, options): build the MongoDB queue, with specified name (async)

• the specified options are passed as is to Mongo-Queue - see [https://github.com/chilts/mongodb-queue]
• visibility will default to 10 minutes if not specified, to avoid processing an update twice if the remote is taking too long

• getSyncState(db, collectionName): get sync storage object (async)
• getLocalConnection(db, pipes): local connection, with collections as per pipes (async)

The local connection will have collection instances created according to the pipe configuration, which should include either a fields array or a localKey value.

localKey can be either a string or an array of strings, and if it is not specified it will default to the first fields in the fields array. A unique index will automatically be created on that field (or fields) if one does not already exist.

Methods of local collection instances:

• get: find a single record, extracting keys from the given selector
• find: find a set of record using an arbitrary query
• update: update one or more record using an arbitrary query or an object id It's possible to pass a MongoDB operation instead of a record. Because it's a bit of a hack, the library will only recognize the operations that contain one of these operators: $push, $set, $unset.
• upsert: upsert a single record If the record contains some keys that start with a $ sign, they will be interpreted as MongoDB operations.
• remove: remove records matching a selector
• addOrUpdateChildInCollection
• removeChildFromCollection

Methods of the queue:

• get
• add(payload, options) - options are the same as for Mongo-Queue
• ack

Methods all return a promise.