Change CC-BY * links to newest versions

[LouCypher]

Current links on userstyles.org:

• http://creativecommons.org/licenses/by/3.0/
• http://creativecommons.org/licenses/by-sa/3.0/
• http://creativecommons.org/licenses/by-nd/3.0/
• http://creativecommons.org/licenses/by-nc/3.0/
• http://creativecommons.org/licenses/by-nc-sa/3.0/
• http://creativecommons.org/licenses/by-nc-nd/3.0/

Newest:

• http://creativecommons.org/licenses/by/4.0/
• http://creativecommons.org/licenses/by-sa/4.0/
• http://creativecommons.org/licenses/by-nd/4.0/
• http://creativecommons.org/licenses/by-nc/4.0/
• http://creativecommons.org/licenses/by-nc-sa/4.0/
• http://creativecommons.org/licenses/by-nc-nd/4.0/