Update of the packaging requirement page

I have made some rewrite of the page:

	https://www.w3.org/dpub/IG/wiki/Portable_Package_Requirements

Actually, it is now available from a different URI, too:

	https://www.w3.org/dpub/IG/wiki/Requirements_for_Web_Publication_and_Packaging

which reflects the name better.

Any change/critique/comment are welcome!

Thx

Ivan

----
Ivan Herman, W3C
Digital Publishing Activity Lead
Home: http://www.w3.org/People/Ivan/
mobile: +31-641044153
ORCID ID: http://orcid.org/0000-0003-0782-2704