Updated as_variable_name to Python 3
Merge pull request #453 from schryer/master

Updated as_variable_name to Python 3
Add desktop file
update example to reflect current API
Update documentation to reflect current API
More Python 3 fixes
More fixes
Use string type for categorical data because Python 3 cannot sort list with mixed float and string types
Added workaround for Astropy bug in Python 3
Fixed more tests
Fix img_data factory when PIL is not present
Fix object comparison in Python 3
Fix comparison
Fix categorical data so that it uses strings but can use NaN or None to indicate no category
Fix test failure in d3po exporter
Test everything except glue/qt in Python 3.4
Fix PATH
Fix Python version
pyside is not available in anaconda for Python 3.x
Fix syntax