Corrects default configuration to test server
Lets user set per-service url settings when instatiating services

If the user wants to use different url settings (i.e. protocal,
domain or port) for a specific service, he can do so by adding a
service-entry when instatiating the services.

For example,

var services = new StudioServices({
        server: {
            domain: 'studio3.craftercms.org',
            port: ''
        },
        api: {
            base: 'api'
        },
        Asset: {
            domain: 'localhost',
            port: 3000
        }
    });
Sets default value for custom config