Update obsolete "Message Delivery Receipts" support from (JEP|XEP)-0022 to XEP-0184

When Smack was written JEP-22 was the specification for "Message Delivery Receipts". JEP-22 has been declared obsolete in favor of XEP-0184.

We need to update the documentation, fix broken links, find the differences in the two specifications and adapt the code.

Related files and changesets (this list is incomplete):

• http://fisheye.igniterealtime.org/browse/~br=trunk/smack/trunk/documentation/extensions/messageevents.html

• http://fisheye.igniterealtime.org/changelog/smack?cs=2024

XEP: http://xmpp.org/extensions/xep-0184.html