use ar-extensions to import districts/schools from nces_data
use ar-extensions to import districts/schools from nces_data

Speeds up this task by about 100x:

  rake portal:setup:create_districts_and_schools_from_nces_data

time RAILS_ENV=production jruby -J-Xmx2048m --server -S rake portal:setup:create_districts_and_schools_from_nces_data

now takes about 5:36
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