Provide event info for binary manipulation

[Jotschi]

It would be useful for external caching systems to have additional event information that includes binary uuids / filenames.

Currently a binary field update just triggers a regular node.updated event. There is no information included that the binary field xyz was updated. We could either add the binary uuid/s to the event or provide additional events that cover this aspect (e.g. binary.updated, binary.deleted, binary.created).

[Jotschi]

Potential place for binary updated: https://github.com/gentics/mesh/blob/dev/core/src/main/java/com/gentics/mesh/core/endpoint/node/BinaryUploadHandler.java#L368 or in BinaryStorageSystem (preferred)