Domain specific config files

[toniwidmo]

Allow multiple BlockPress sites to run from a single installation, by allowing multiple domain specific config files. Suggested order of preference for loading config for https://example.domain.name:

• example.domain.name.config.json
• example.domain.config.json
• example.config.json
• local_config.json
• config.json <--- the default site settings when no user specified settings are defined.