Logback appender should use formatted message

Logback appender should use the formatted message instead of the plain one.
Merge pull request #15 from felixhamel/patch-1

Logback appender should use formatted message
Adjusted snap-ci build image
Updated Readme, fix #16
Fixed bug on jedis pool caching
Merge pull request #17 from Batigoal/master

Redis bugfix and GelfSender flexibility
Prepared release 1.4.1
[maven-release-plugin] prepare release logstash-gelf-1.4.1
[maven-release-plugin] prepare for next development iteration
Added download page to docs
Code Cleanup #19
Code Cleanup #19
Configuration of default field names #20
Configuration of default field names #20
Github site integration
Github site integration, added LICENSE file to sources
Added support for travis-ci
Merge remote-tracking branch 'origin/master'
Added support for travis-ci
Redis and commons-pool2 dependencies needed when not using redis #21