fix the issue brought by 0.10.0 that Spring related classes are mistakenly loaded via DefaultInjector, which causes exceptions when there is no Spring libraries available.

hibernate will persist every changes made to entities during the session, so in ConfigChangeContentBuilder case, we should clone the entity first to not trigger unnecessary writes to the db

1. Enable config cache to improve config service performance, just set
config-service.cache.enabled to true in ServerConfig
2. Normalize the namespace name in case the one provided has character
case issue

app's admin can create private namespace. & default create namespace when create public appnamespace