Adding my name to authors/contributors. I'm waiting to hear

back from Carnegie Mellon about whether they're interested in
signing the agreement (do you know if they have already?).
In the meantime, I'm submitting these changes on my own time.
If CMU has already signed the corporate contributor agreement,
please remove my name from the AUTHORS list.

R=rsc
https://golang.org/cl/154161

AUTHORS

@@ -9,6 +9,7 @@
 # Please keep the list sorted.
 
 Abhinav Gupta <abhinav.g90@gmail.com>
+David G. Andersen <dave.andersen@gmail.com>
 David Titarenco <david.titarenco@gmail.com>
 Devon H. O'Dell <devon.odell@gmail.com>
 Google Inc.

CONTRIBUTORS

@@ -34,6 +34,7 @@ Bill Neubauer <wcn@golang.org>
 Brendan O'Dea <bod@golang.org>
 Cary Hull <chull@google.com>
 Daniel Nadasi <dnadasi@google.com>
+David G. Andersen <dave.andersen@gmail.com>
 David Symonds <dsymonds@golang.org>
 David Titarenco <david.titarenco@gmail.com>
 Devon H. O'Dell <devon.odell@gmail.com>