Config server with settings

Added setting interface (ServerSettings and ServerInternalSettings) for server to access its configuration properties.

Enabled to obtain a server property with Config.get + property settings. Replaced the previous Apache Configuration + constant string property-accessing-pattern. 
A simple test "testNormalizedRelativeURI" is included in SettingsTest to ensure all the NORMALIZED_RELATIVE_URIs get from Config interface is in the correct format.