Added functionality to Config to allow overriding local.conf with a spec...

...ified conf file

The system property name is: local.conf.override and can be found in the Config object as a constant. It is the pointer to where the overriden file is to be found. It can be an absolute or relative path.
This property should not be used outside of this class so it do not need to be exposed. Also it is only used in one place, so it would be easier to just inline the usage.

getLocalConfFile(defaultLocalConf:String = "local.conf") - this does not need to take a parameter, just return local.conf as the default value in the next line.