I did couple of fixes and improvements of the plugins directory code and would like to have them deployed to the live site.

The changes are already merged to the moodle.org-2.8-test branch and include:

• fix of MDLSITE-3753: We now throw error only when the user marks the supported version lower than the one declared as required in version.php
• the Supported Moodle version is now required field
• small visual fixes in the plugin version editing form ("Can be updated from", "Alt download URL" and "Changelog URL" moved and set advanced)
• release notes and plugin description now displayed at more prominent place at the page
• the 'Rename root directory' is enabled by default
• validation messages styling fix
• fix of potential privacy issues rendering
• contributors have to explicitly declare they have checked the Plugin contribution checklist before uploading a new ZIP