Hello team, As spring 4 & spring boot 1 have reached end-of-line according to [official announcement](https://spring.io/blog/2019/08/06/it-is-time-goodbye-spring-boot-1-x), start from servicecomb-java-chassis 2.0, we are going to remove all modules provided for spring 4 & spring boot 1.
Some details information: 1. remove all dependencies management: remove java-chassis-dependencies-spring4, java-chassis-dependencies-spring4, java-chassis-dependencies-spring-boot1, java-chassis-dependencies-boot2, and all of them are combined into one java-chassis-dependencies. 2. remove all starters for spring boot 1, includes spring-boot-starter-discovery, spring-boot-starter-registry, spring-boot-starter-provider, spring-boot-starter-transports, spring-boot-starter-zuul, spring-boot-starter-zuul-zipkin, etc. In the future, we only provide spring-boot2 starters. Generally, we only keep spring-boot2-starter-standalone, spring-boot2-starter-servlet, and these two modules will renamed according to spring-boot conventions. Other starters will become [spring cloud huawei](https://github.com/huaweicloud/spring-cloud-huawei). Servicecomb-java-chassis will focus on it's main features. Any suggestions?
