Refactor how properties files are read from server

We should load the files in the following order:

Application.properties Application_xx.properties //1 Application_xx-YY.properties //2

1 if lang is specified as 'xx' or 'xx-YY' (for instance: 'en', 'en-US'); 2 if lang is specified as 'xx-YY'

Load order should be reversed as from today. Load the bottom-up from less to more specific and override the keys.