Allowed overriding name of settings files so that multiple environments can use the same files.

Specifying a directory in /settings: will use the existing behavior of
looking for files names of {{Environment}}.js and
{{Environment}}.servermaps, while specifying a .js file will result in
using that specified file and the same name with a .servermaps
extension. For example, specifying /environment:testing
/setting:general.js will use general.js and general.servermaps, even
though the environment name is 'testing'.