CI: drop test against Python 3.3
CI: drop test against Python 3.3

pandas 0.17.0 isn't available on conda for 3.3

gregcaporaso/scikit-bio,kdmurray91/scikit-bio,anderspitman/scikit-bio,kdmurray91/scikit-bio,anderspitman/scikit-bio,gregcaporaso/scikit-bio