fix: show commands with --help

[flandrade]

Fixes #707

Issue

When --help or version are provided, yargs exit the process before loading the commands and the view helper.

Output with --help:

Options:
  --help     Show help                                                 [boolean]
  --version  Show version number                            [boolean]

Output with --version:

5.3.0

Solution

Add exitProcess(false) so the process doesn't exit before loading the commands. In addition, help and version are also disable so they don't get printed when loading yargs.

help and version are enabled when loading the modules.

Output with --help:

Sequelize CLI [Node: 10.13.0, CLI: 5.3.0, ORM: 4.41.0]

sequelize [command]

Commands:
  sequelize db:migrate                        Run pending migrations
  sequelize db:migrate:schema:timestamps:add  Update migration table to have timestamps
  sequelize db:migrate:status                 List the status of all migrations
  sequelize db:migrate:undo                   Reverts a migration
  sequelize db:migrate:undo:all               Revert all migrations ran
  sequelize db:seed                           Run specified seeder
  sequelize db:seed:undo                      Deletes data from the database
  sequelize db:seed:all                       Run every seeder
  sequelize db:seed:undo:all                  Deletes data from the database
  sequelize db:create                         Create database specified by configuration
  sequelize db:drop                           Drop database specified by configuration
  sequelize init                              Initializes project
  sequelize init:config                       Initializes configuration
  sequelize init:migrations                   Initializes migrations
  sequelize init:models                       Initializes models
  sequelize init:seeders                      Initializes seeders
  sequelize migration:generate                Generates a new migration file                                                       [aliases: migration:create]
  sequelize model:generate                    Generates a model and its migration                                                      [aliases: model:create]
  sequelize seed:generate                     Generates a new seed file                                                                 [aliases: seed:create]

Options:
  --help     Show help                                                                                                                               [boolean]
  --version  Show version number                                                                                                                     [boolean]

Output with --version:

Sequelize CLI [Node: 10.13.0, CLI: 5.3.0, ORM: 4.41.0]

5.3.0

Other changes

• Since version 9.0, yargs are enabled by default, so it's not required to add help() to each command. See yargs' changelog.

[sushantdhiman]

Can you show output for sequelize db:migrate --help

[sushantdhiman]

Seems to work well, thanks @flandrade

sequelize db:migrate --help

Sequelize CLI [Node: 8.11.3, CLI: 5.3.0, ORM: 4.39.0]

Options:
  --help             Show help                                                                                                              [boolean]
  --version          Show version number                                                                                                    [boolean]
  --env              The environment to run the command in                                                          [string] [default: "development"]
  --config           The path to the config file                                                                                             [string]
  --options-path     The path to a JSON file with additional options                                                                         [string]
  --migrations-path  The path to the migrations folder                                                               [string] [default: "migrations"]
  --seeders-path     The path to the seeders folder                                                                     [string] [default: "seeders"]
  --models-path      The path to the models folder                                                                       [string] [default: "models"]
  --url              The database connection string to use. Alternative to using --config files                                              [string]
  --debug            When available show various debug information                                                         [boolean] [default: false]
  --to               Migration name to run migrations until                                                                                  [string]
  --from             Migration name to start migrations from (excluding)                                                                     [string]