Add Module Commands support

Two suggestions and one FIX (outdated, see comment) :

Suggest 1 -> 72701f4 (code) and ef3292f (doc) Is a simple snippet that allows to run commands from a module by adding the `command` into the **module.json**. I also wrote the corresponding documentation.

Suggest 2 -> 768765c 5f08f4a (code) and 1dd7487 (doc) Allows modules to register Aliases for modules Facades.

Fix -> (8b0f5c0 (code) and de76c0b (doc) Is a simple fix for the situation : You have multiple paths and you specify the Finder config in Manual mode. Laravel-Modules cound not determine the default path to use because `path` will be an array.) So simple fix is allow to specify the `path` for each module in `modules` configuration value. See the documentation example in de76c0b