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.

2. adjust client side's long polling timeout from 600 seconds to 90 seconds

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