add pandas to the dependencies

Author: wkerzendorf

.travis.yml

@@ -11,7 +11,7 @@ notifications:
 
 env:
   global:
-    - CONDA_DEPENDENCIES="pytest pytest-cov numpy astropy"
+    - CONDA_DEPENDENCIES="pytest pytest-cov numpy astropy pandas tables"
     - PIP_DEPENDENCIES="codecov"
   matrix:
     - PYTHON_VERSION=2.7