Perform indexing within database transaction

Prevents objects from being queried while their indexes are being filled
Fix Channel index progress notification bugs

`Bucket.addObjectWithGhost(Ghost ghost)` is async so `Channel` would notify before object was saved to the database. Adding `Bucket.addObjectWithGhost(Ghost ghost, Runnable afterSaved)` to allow the `IndexProcessor` to notify after object is persisted.
Coding style fixes

- Space between closing paren and opening curly brace ") {"
- private/protected scope member fields are prefixed with 'm'