Test enhancement

[peter279k]

Changed log

• Remove php-5.6 test in Travis CI build.
• Require php-7.0 at least in composer.json.
• Enhance Travis CI setting.
• Remove bootstrap because we can only use the vendor/autoload.php file.
• Define test namespace in composer.json.
• Fix indents.

[jorgecc]

Can you cancel it?. I agree with the changes; however, I can't limit PHP 5.6 because it is still alive. I know that it's discontinued, but PHP 5 is still king, so there is no reason to not to use PHP 5.6 but the use of new features (that AFAIK this library is not using).

Php trend 16 september

[peter279k]

@jorgecc, thank you for your reply. I push the latest commit and revert php-5.6 support.

You can check that.