Removed names from certain -spec attribute.

Interpreted based on the names associated with the parameters in the
actual function implementation.
Updated documentation of ydb_ets_mgr module.

Added -spec attributes on all functions.

Fixed issue where the result of processing the {ready, ...} request was
not returning the correct tuple-list. Changed to yield {Id, undefined}.
Created generic bolt process.

Extends generic publisher process. Communicates with the ETS manager to
determine when all of the publishers it subscribes to are ready, in
in order to compute the schema.

Defines callbacks for processing and emitting tuples.
Added support for creating managed ETS tables.

The heir of the table is set as the manager, so that in case the
receiving process dies, the table under ownership of the manager.

Currently the manager does _not_ support state recovery; meaning that
requests made by a restarted process for a table will **always** return
a new ETS table right now.