change travis to python 3

.travis.yml

@@ -19,7 +19,6 @@ sudo: true
 env:
     global:
         - COMPILER=gcc
-        - PANDAS_VERSION=0.16
         - ASTROPY_USE_SYSTEM_PYTEST=1
         - SETUP_CMD='test'
         - TEST_MODE='normal'

ci-helpers/install_tardis_env.sh

@@ -2,18 +2,12 @@
 cd $TRAVIS_BUILD_DIR
 if test -e $HOME/miniconda/envs/tardis; then
     echo "TARDIS env already installed.";
-    # Also check for tardis_env27.yml change
+    # Also check for tardis_env3.yml change
 else
-   conda env create -f tardis_env27.yml
+   conda env create -f tardis_env3.yml
    #trouble with building due to segfault at cython (https://github.com/cython/cython/issues/2199)
    #remove if we can get normal cython through conda
-   source activate tardis
-   conda uninstall -y cython
-   git clone https://github.com/cython/cython
-   cd cython
-   git checkout c485b1b77264c3c75d090a3c526de24966830d42
-   CFLAGS="$CFLAGS -D CYTHON_CLINE_IN_TRACEBACK=0" python setup.py install
-   cd ..
+   source activate tardis3
 fi
 
-source activate tardis
+source activate tardis3