Add a new parameter "newline" to LogStashJSONLayout that formats compact events on separate lines.

From docs:
 If "true", adds newline after each event, only applicable when compact=true, defaults to "false".
Merge pull request #1 from finn-no/feature/newline-between-compact-events

Add a new parameter "newline" to LogStashJSONLayout that formats compact  events on separate lines.