Update load.py to skip excluded variables in EA

'Exclude from D-PLACE?' column was added to ea_variable_names in Cultural_traits_database_Feb14_2014_wiki.xlsx

Fixes #27
Add N field to EAVariableCodeDescription
Migration for adding n to EAVariableCodeDescription
Update load.py to for ea_codes.csv

Handle additional column in ea_codes from Cultural_traits_database_Feb14_2014_wiki.xlsx
Handle case with data for excluded EAVariableDescription (due to #27)
Update load.py for ea_vals.csv

‘EA_id’ column was changed to ‘ID’ in
Cultural_traits_database_Feb14_2014_wiki.xlsx
Suppress warning about non-existent EAVariableDescription
Update language models for Revised Ethnologue families - Feb 10 2014

Removed LanguageFamily object and renamed others
Revert "Update language models for Revised Ethnologue families - Feb 10 2014"

This reverts commit 6b9a79ebdd7f1b9b8fa8a63ebb115205cd38ee94.
Update language models for Revised Ethnologue families - Feb 10 2014

Removed LanguageFamily object and renamed others
Update load.py for Revised Ethnologue families - Feb 10 2014

Handle empty cells in Class2/Class3, rename/discard unused fields

Fixes #31
Migration for lang model changes due to Revised Ethnologue families - Feb 10 2014
Remove code.save from migration
Cascade changes from removing LanguageFamily
Update load_all_datasets.sh for newest langs
Remove newline from file name
Merge pull request #36 from NESCent/revise-load

Update load scripts for latest Feb datasets from WG