PySide; python_version != '2.7'
imread; 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

Remove imread from the optional requirements for 2.7
Remove imread from the optional requirements for 2.7
