Transparent testing command

[sagikazarmark]

I've found a way to make the used testing command transparent from several points of view:

https://github.com/indigophp/boilerplate/blob/package/composer.json#L25

Why is this good?

1. We can have the same instructions for all repos: composer test. This way we can easily maintain CONTRIBUTION guides, since they don't depend on the used testing framework.
2. The same above is true for travis config: https://github.com/indigophp/boilerplate/blob/package/.travis.yml
3. It is simple and consistent. Whatever testing framework we use, this command can remain the same.

@ddeboer you are as concerned about package details as me. What do you think?

[ddeboer]

I like it! Please submit a PR.

[sagikazarmark]

Done #8

[Baachi]

Cool thing, didn't noticed this feature 👍