Lib and build upgrade in order to stay compatible to spring boot 2.2.0 and above

Upgraded Jedis dependency to version 3.1.0,
Upgraded various Maven plugin versions,
Use openjdk 11 to build (Still 1.8 source/target language level though)

supports PUBLISHing messages to redis (issue #24)

1.4.0

prepares release 1.4.0

Refactoring: Separation of concerns

moves connection-, buffering/message sending functionality from appender to sperate classes

Timer uses daemon-thread

When Timer used a user-thread, the JVM didn't shutdown without explicit RedisBatchAppender-shutdown. Logback's shutdown-hook wasn't called (because it's called when all user-threads ended) and the JVM hung.

With Timer using a daemon-thread the shutdown hook is called and shuts down the Appender

Maintenance - Upgraded logback versions

Lr 16 update logback version (#18)

* LR-16 raised version for logback to 1.2.3 and fixed implementation issues

maintenance - update dependencies

see PR #17

0.9.3 maintenance release

#12 updates build status badge source thx @roechi
#10 prepare release process to maven central thx @lkwg82
#9 Improve resilience should fix #8 enhancement thx @lkwg82
#7 fixes NPE in RedisBatchAppender while stopping bug thx @matonthecat
#5 removes bad default WaitStrategy in demo snippet enhancement thx @lkwg82
#4 Forgiving application startup fixes #2 thx @lkwg82
#3 Cleanup pom enhancement thx @lkwg82
#1 enables RedisBatchAppender to log access logs thx @lkwg82