[racket] Ubuntu PPA update for 6.1

From: Asumu Takikawa (asumu at ccs.neu.edu)
Date: Tue Aug 5 02:21:48 EDT 2014

Hi all,

The Ubuntu PPA for Racket has been updated to v6.1:
  https://launchpad.net/~plt/+archive/ubuntu/racket

There are only packages for trusty and precise this time (the others
have been deprecated on the build server).

Let me know if you have any issues. I may not respond very quickly
though due to travel.

Cheers,
Asumu

Posted on the users mailing list.