CI: only use "diffpy" channel in conda build

The "diffpy" channel has recent libobjcryst.

Author: pavoljuhas

.travis.yml

@@ -66,8 +66,6 @@ before_install:
   - $NOMC || conda install --yes conda-build conda-verify jinja2
   - $NOMC || conda create --name=testenv --yes $MYCXXCOMPILER
   - $NOMC || conda config --add channels diffpy
-  # FIXME - keep just the "diffpy" channel for public release.
-  - $NOMC || conda config --add channels diffpy/channel/dev
 
   - $NOAPT || test "${TRAVIS_OS_NAME}" = "linux" || exit $?
   - $NOAPT || sudo apt-get update -qq