Allow creation of "flat" modules

[weierophinney]

Feature Request

Q	A
New Feature	yes
RFC	no
BC Break	no

Summary

When creating a new application from the skeleton app, users are prompted with regards to the preferred directory structure they want for the "App" module. They can choose from no modules created, to the default of using a "flat" structure (creates src/App/, and puts only PHP class files in it) or the "recommended" structure (creates src/App/ with additional src and templates directories beneath it; class files are under src/App/src/).

Currently, the "module:create" command creates a "recommended" module structure:

- src/
  - {ModuleName}
    - src/
      - ConfigProvider.php
    - templates/

Considering the skeleton offers a "flat" structure as well, I recommend we add an option to the module:create command to create a "flat" module:

- src/
  - {ModuleName}
    - ConfigProvider.php

When doing so, the ConfigProvider should omit the "templates" configuration.

I recommend the option name --flat for this.

[weierophinney]

Completed with #13, to release with 2.0.0.