Refactor Spring Context initialization to a factory class

- RestApplication class no longer contains Spring context initialization
  code
- Remove compile-time dependency in rest module on core.AppConfiguration
  (in the core module)
- Added name attributes to property source file configurations
- Fix Heroku startup issue related to location of properties file (format
  needed to be file:///path)
- Set log level on org.springframework.core.env.PropertySourcesPropertyResolver to DEBUG
- Add extra logging