Fix Hoa\Test with Composer

[Hywan]

This PR does several things:

1. atoum/atoum has been forked in hywan/atoum,
2. a tag has been added on hywan/atoum to get rid of the minimum-stability properties in composer.json,
3. we keep the HOA_ATOUM_* environment variables but we look for the atoum binary in the vendor/bin/ directory.

The fork is temporary! See discussion and related links at https://github.com/hoaproject/Test/issues/8. Only hoa test:run is up-to-date and works with Composer right now (but it is enough for the beginning!).

What is the modus operandi to test a library now?

1. get a library (by cloning for example),
2. run composer install --dev,
3. run vendor/bin/hoa test:run -d Test.

atoum, the Praspel's extension and all dependencies are installed automatically.

I think we can open a new PR to automate the -d Test part if there is no file selected.

Next step:

• update hoa test:generate,
• update hoa test:clean,
• update all composer.json of all libraries that have tests with "require-dev": { "hoa/test": "~…" } because --dev is not recursive.

When this PR will be accepted, I propose to finalize this library just after.

Thoughts?

[vonglasow]

:+1:

[thehawk970]

+r :+1: