talksapp: allow running without GitHub creds on devappserver

Tests are failing because of this, also removed the addition
of context to errors since it breaks the check for IsNotFound
that decides what status code to return.

Fixes #441.

Change-Id: Ib7f41370ad2d1c67c80b0b34be17c72beb1a5077
Reviewed-on: https://go-review.googlesource.com/28780
Reviewed-by: Chris Broadfoot <cbro@golang.org>
1 file changed