Remove the IAXy firmware from Asterisk.

The firmware can now be found on downloads.digium.com, where the rest of our
binary downloads live.  This was the last part of our Asterisk tarballs that
was considered non-free by Debian.  :-)

(closes issue #15838)
Reported by: paravoid


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@218798 65c4cc65-6c06-0410-ace0-fbb531ad65f3

UPGRADE.txt

@@ -8,6 +8,12 @@
 
 IAX2:
 
+* The firmware for the IAXy has been removed from Asterisk.  It can be
+  downloaded from http://downloads.digium.com/pub/iaxy/.  To have Asterisk
+  install the firmware into its proper location, place the firmware in the
+  contrib/firmware/iax/ directory in the Asterisk source tree before running
+  "make install".
+
 * There have been some changes to the IAX2 protocol to address the security
   concerns documented in the security advisory AST-2009-006.  Please see the
   IAX2 security document, doc/IAX2-security.pdf, for information regarding