use guice module better in app framework

There are multiple issues with using guice module in app framework.

1. ApplicationProviderServiceImpl is instantiated twice

2. the interface between application and eagle server is not clear. It is not correct to only let application to register submodules,, instead it should includes some state inherited from eagle server, for example metadata storage type.

3. not necessary to use module scope, it is pretty over-engineering when application only want to register some module.

4. MemoryMetadataStore should use singleton