Build a config.yml metric provider selector

[ribalba]

Currently you need to go into the config.yml by hand and fiddle around with the metric providers by hand by uncommenting lines. This is quite cumbersome and annoying. It should be fairly easy to write a little npyscreen[1] script that gives you a nice interface.

You can use the NPSAppManaged to display various options

Please note that npyscreen is not maintained anymore and should not be used in production.

[1] npyscreen