PySide; python_version != '2.7'
imread; python_version != '2.7' and python_version != '3.2'
SimpleITK; python_version != '3.2' and python_version != '3.4'
astropy
tifffile

PySide; python_version != '2.7'
imread; python_version != '2.7' and python_version != '3.2'
SimpleITK; python_version != '3.2' and python_version != '3.4'
astropy
tifffile
imageio

Add imageio to optional reqs
Add imageio to optional reqs
