Fix escape of attribute values (\t \n \r) (EXMPP-64)

In attribute values, the character information items TAB (#x9), newline
(#xA), and carriage-return (#xD) are represented by "&#x9;", "&#xA;",
and "&#xD;" respectively.
Fix few mistakes in namespace defines.
exmpp_session.erl : return bounded JID for ANONYMOUS auth
Just check http request code, don't verify reason phrase part
Properly handle empty initial <body/> in http-bind
Merge remote-tracking branch 'upstream/master'