Add piwik header to all .php files #524

All Piwik PHP files should contain the following header:

<?php
/**
 * Piwik - Open source web analytics
 * 
 * <a class='mention' href='https://github.com/link'>@link</a> http://piwik.org
 * <a class='mention' href='https://github.com/license'>@license</a> http://www.gnu.org/licenses/gpl-3.0.html Gpl v3 or later
 * <a class='mention' href='https://github.com/version'>@version</a> $Id: $
 * 
 */

Attachment:
hasheader.pl

I'd like to suggest adding an explicit copyright statement.

(In [1259]) Fixes #524 - add standard Piwik header to .php files in core & plugins, with
the exception of those in core/Updates/.

Use attached script to identify files without the required header:

find core -name '*.php' -exec perl hasheader.pl {} \;
find plugins -name '*.php' -exec perl hasheader.pl {} \;

(In [1698]) refs #524 - add standard header