Removed irrelevant configurations

- Removed irrelevant configurations and respective implementations for delivery path message content
  caching

- Removed batching state event updates for messages. Since there is no performance improvement in
  batching (No database calls etc. ) It only adds additional maintenance of an ArrayList and more
  work for GC after clearing list on each batch update

- Thread pool executor used for asynchronous processing of acknowledgements is removed. Now the Same
  behaviour is achieved through disruptor.
Merge pull request #219 from Asitha/configuration-update

Removed irrelevant configurations