Use predictable column names when no user-provided name is available
Fix example program
Use default column names for groupby operations
Override inferred column names that don't match the current column
Comments for resolve_attribute_name
Use default column names for stateful apply
Tweak groupby example
Fix remaining groupby examples
Test of default column names
Fix groupby examples to match schema of query_tests.py
Use public user for query_tests.py data
Create a relation_key if the user provides a string
Fix default_column_names test to use canonical output variable
Change default column name
Merge pull request #148 from uwescience/andrew_column_names

Use predictable, boring column names when user fails to specify a real name