Add option to ignore sub dependencies checking

[valentinloiseau]

Implement #30

Add an option ignore-sub-dependencies and check if a package is required in root.

[soullivaneuh]

Thanks and sorry for the delay. I'll try to give a look as soon as possible.

[soullivaneuh]

@valentinloiseau Could you please rebase your PR against the master branch?

[valentinloiseau]

Rebased ✅

[soullivaneuh]

@valentinloiseau Looks like I have an issue with Travis. I'll inform you when this is fixed.

[soullivaneuh]

You may rebase once #72 is merged.

[valentinloiseau]

@soullivaneuh An other issue with Travis?

[soullivaneuh]

Yes, but I don't understand this error. Happens sometimes.

Thanks for the rebase, I'll do a review later.

[soullivaneuh]

Could you please complete package check tests with the root option case?

[soullivaneuh]

Suggested change

	* `ignore-sub-dependencies`: Shows only outdated package required in composer.json.
	* `ignore-sub-dependencies`: Shows only outdated root packages.

We may also rename the option to something like root-packages-only to be consistent with the code naming. What do you think?

[valentinloiseau]

Sounds good, I'll do it

[valentinloiseau]

@soullivaneuh It's done

[rcerljenko]

@soullivaneuh can you address this please. It seams that @valentinloiseau has done it. :)

[valentinloiseau]

@soullivaneuh ping

[dereuromark]

You can now PR against maintained https://github.com/dereuromark/composer-versions-check