Revert "code.google.com/p/go.talks -> github.com/bsiegert/talks."

This reverts commit 5541bd9c2b2e5bc23bbfd413802eb0ed94c67e19.
(cherry picked from commit 84854b0c7156d5b25913b854a8bc9528338204a5)
Pull in latest changes from go.talks subrepo.
(cherry picked from commit bb25564350f2781fa1e589c45750e8c3bb0a98a1)
Use // +build !appengine, as this does not work on GAE, period.

https://codereview.appspot.com/7341051
(cherry picked from commit 24134e6f27d0e9989161838620d8f815d06fcb07)