composer validate

[szepeviktor]

Please add the validate command.
e.g. The WC plugin has many problems.

./composer.json is valid for simple usage with Composer but has
strict errors that make it unable to be published as a package
See https://getcomposer.org/doc/04-schema.md for details on the schema
# Publish errors
- description : The property description is required
# Lock file errors
- The lock file is not up to date with the latest changes in composer.json, it is recommended that you run `composer update` or `composer update <package name>`.
# General warnings
- No license specified, it is recommended to do so. For closed-source software you may use "proprietary" as license.
- The version field is present, it is recommended to leave it out if the package is published on Packagist.
- require.psr/log : unbound version constraints (*) should be avoided