Improvements

• upgraded byte buddy to 1.9.15 #448
• upgrade to open tracing api 0.33.0, jaeger 0.35.5 #449
• switch to java 8 as minimum #453
• upgraded weasel
• upgraded eum server to spring boot 2.1.7
• remove the sun.misc.Unsafe usage #452
• added Elasticsearch 7 support
• #455 test if com.sun.xml.ws:jaxws-rt is present (#462)