Minor Mistakes in 4.7.0 ftp image

[Joel Sherrill]

Hi,

I accidentally left the 4.6.99.3 add-on package
in the 4.7.0 tree.  I have corrected this.

I also noticed that the RTEMS specific version
of MDP (Multicast Dissemination Protocol) package
is in contrib.  I thought the patches were merged
back to the official distribution.  Can someone
confirm that?  I would like to remove the old
MDP version and replace it with a README and pointer.

--joel