Introducing universal logger

[alexzerntev]

Added scala and java key-value pair logger

• The raw loggers are built on top of normal loggers. In scala it can be used in an exact same way as StrictLogging. The PR is backward compatible so we can gradually switch to the new logger. Java logger uses the decorator pattern and wraps internally the org.slf4j logger

[miguelbranco80]

Some issues to think about...

[bgaidioz]

If one inherits the TraceIdLogging trait, it can set the trace ID with the dedicated methods (as the name indicates), but also has access to the inner ContextLogging methods that permit to add any random key to MDC. Just wondering if that could be a problem.

[bgaidioz]

The interface and what it leads to in the log files looks convenient.