Integrate the "Create your own framework" tutorial into the Symfony official documentation

The "Create your own framework" tutorial I've published on my blog at the beginning of 2012 is still very popular based on the traffic it still receives. Problem is that those articles are not up to date anymore. The RST files on my Github account have been updated though.

So, as there is a lot of interests, and because the up-to-date version is not easily browseable, I propose to integrate the tutorial into the Symfony official documentation and website.

That will also let more people have a look at it and perhaps improve the documentation over time.

given that you haven't created a phpunit.xml file defining that only the ``src`` folder should be covered (or at least that the ``vendor`` one should be excluded), PHPUnit will include all vendors in the coverage, and for that it will load all PHP files. Given that some vendors are containing bin scripts, it may create weird side-effects (for instance, it does really weird things when your vendors contain Doctrine because the Doctrine bin exits with an error when you don't create a config file alongside it to provide the database settings). It may be a good idea to include the coverage configuration in the phpunit.xml file created at the beginning of the chapter