make the env install faster

Author: ocefpaf

.travis.yml

@@ -42,6 +42,7 @@ before_install:
     conda config --add channels conda-forge --force
     conda install pycryptosat
     conda config --set channel_priority strict
+    conda config --set safety_checks disabled
     conda create --name TEST python=$PY --file requirements.txt --file requirements-dev.txt
     source activate TEST
   # Install firefox headless driver.