DEV: add diffpy/dev channel for conda builds.

This is necessary for Python 3 builds that need development
version of libobjcryst.

Revert after public release of the Python 3 pyobjcryst.

Author: pavoljuhas

.travis.yml

@@ -65,6 +65,8 @@ before_install:
   - $NOMC || cp ~/mc/bin/scons ~/bin/
   - $NOMC || conda create --name=testenv --yes python=${MYPYTHON_VERSION} coverage
   - $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