Add --no-check-all option to composer validate command

Example with Packagist project.

Without option:
```
$ composer validate
Reading ./composer.json
./composer.json is valid for simple usage with composer but has
strict errors that make it unable to be published as a package:
See http://getcomposer.org/doc/04-schema.md for details on the schema
name : is missing and it is required
require.hwi/oauth-bundle : unbound version constraints (dev-master) should be avoided
require.snc/redis-bundle : unbound version constraints (dev-master) should be avoided
require.kriswallsmith/assetic : unbound version constraints (@dev) should be avoided
require.pagerfanta/pagerfanta : unbound version constraints (@dev) should be avoided
```

With option:
```
$ composer validate --no-check-all
Reading ./composer.json
./composer.json is valid for simple usage with composer but has
strict errors that make it unable to be published as a package:
See http://getcomposer.org/doc/04-schema.md for details on the schema
name : is missing and it is required
```