Make Rails arguments optional

[Rukomoynikov]

Calling rails-new without any arguments fails with error: (error: the following required arguments were not provided: ..). Making rails arguments optional allows to simply run rails-new and see what params are required for scaffolding new rails application (for example app name).

[Rukomoynikov]

Fundamentally it makes <app_name> part of rails commands area. So, rails-new will not have any logic apart from instructions on what ruby\rails version use for building docker image.

Before:

> rails-new

error: the following required arguments were not provided:
  <ARGS>...

Usage: rails-new <ARGS>...

For more information, try '--help'.

After:

> rails-new

Usage:
  rails new APP_PATH [options]

Options:
[--skip-namespace]                                            # Skip namespace (affects only isolated engines)
[--skip-collision-check]                                      # Skip collision check
...

[Rukomoynikov]

If this direction is fundamentally correct I will fix the test.