v2.1.19 Support for Jedis Redis client

⚠️ 🚨 Jump straight to Kamon 2.1.20! This version has a bug when Jedis is not on the classpath!

• kamon-core: Introduce span reporting delay, allowing users to keep Spans in memory for a period of time. Contributed by @ivantopo via #1026
• kamon-akka-http: Fix #1014. Contributed by @SimunKaracic via #1018
• kamon-sqlite: Fix #1008, and update sqlite version. Contributed by @SimunKaracic and @dpsoft via #1023
• kamon-redis: New module, adding tracing for the popular Jedis library. Contributed by @SimunKaracic via #1022