Composer support

[oscarotero]

Hi. I know that one point of the basic idea of this library is:

NO complicated/overengineered code, e.g. no classes/interfaces, test-frameworks, libraries, ... -> It is supposed to be obvious on first glance - even for novices - how this tool works and what it does!

But I think it should be great if the library had some basic support for composer, for easy distribution and use. So, for "advanced users", they can install the library with composer and then execute it with some code like:

require 'vendor/autoload.php';

Pcc::check();

And for novices, just execute the php file phpconfigcheck.php that launch the class and print the result.