LogAppender for java platform/system logger

[justcoon]

similar to slf4j backend implementation

default behavior:

• all annotations are placed at the beginning of log message
• cause - LogAppender.appendCause - as throwable, Cause transformed into FiberFailure
• logger name extracted from Trace, added JPL.loggerName zio LogAnnotation for custom logger name
• updated documentation and examples

open questions:

• slf4j and this jpl implementation got custom logger name aspect, should not we do common one?
• by default both are appending all LogAnnotations-s, including logger name annotation, there is question if this annotation should not be excluded in default setup, because if logger name is extracted from Trace, there is not logger name annotation

related to #322 (from this ticket it is not clear if this was requirement for backend implementation like slf4j or it should be something similar to slf4j-bridge)

[justcoon]

NOTE:
CI setup needs to be updated, as java platform/system logger was introduced at JDK9

[jdegoes]

This should be hidden / made private.

[jdegoes]

This can be a val.

[jdegoes]

Just minor tweaks, and then good to merge!

[justcoon]

@jdegoes - comments solved