Optimizations, Monitoring and Logging

- Made identifiers type-safe
- Changed logging so that most of it is done at debug level instead of info
- Make cluster logging configurable via logback.xml
- Add Bean for looking at the local shards on shard manager
- Add Preconditions in a places where it matters

Change-Id: Ie2b17e89bd88edde1366d0a4d23abf9fb97e6e55
Signed-off-by: Moiz Raja <moraja@cisco.com>