Merge branch 'master' of https://github.com/Batigoal/logstash-gelf into Batigoal-master

Conflicts:
	src/main/java/biz/paluch/logging/gelf/jul/GelfLogHandler.java
	src/main/java/biz/paluch/logging/gelf/log4j/GelfLogAppender.java
	src/main/java/biz/paluch/logging/gelf/log4j2/GelfLogAppender.java
	src/main/java/biz/paluch/logging/gelf/logback/GelfLogbackAppender.java
Merge branch 'Batigoal-master' PR #34