move common.time to omsignal-backend
[build] cleanup the build, remove useless stuff
[build] move core, core-serialization to omsignal-backend
[build] gitignore: ignore logs
[build] Upgrade most dependencies, and remove uneeded ones
Remove ehcache and magic Spring AOP @Caching
UserRepositoryCachingTest: remove this test, as it is now useless
Qs Write API Module: make sure to use the same instance of the event store