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

1. add log output to console for config and admin service
2. remove dev, lpt, tooling logic
3. add default 2 seconds of initial delay to long polling

1. specified cluster
2. data center as cluster
3. default cluster

1. add aop to log spring jpa repository transaction
2. use gson to improve performance
3. specify http message converters for rest template
4. specify content type request header for release operation in portal

1. Add a release key generator to generate human-readable release keys
2. Add retry policy for client long polling
3. Move eureka url config to database