Sources handler

Added

• Accept options object in Origin constructor as last argument.
• Assign to the _id private property the value received in new option "uuid", when received.
• Last argument in Selectors now can be an object containing "defaultValue" and/or "uuid" options.
• Add "sources" handler for managing all instantiated mercury sources as a group.
• Add "config" method to Origin and sources handlers. From now, all Origin implementations can define its own _config method, which will be called with the resultant config each time the "config" method is called.

Changed

• _id private property now is a hash of default id and default value (if no "uuid" option is received)
• Objects without query now will emit "undefined" as "_queryId" property in "cleanAny" events, instead of "null".

Fixed

• Emit _root property on cleanAny events of Selectors.