if you want to import a csv to a heroku table, execute the following command:
psql `heroku config:get DATABASE_URL -a your_app`?ssl=true -c "\copy your_table FROM '/tmp/rows.csv' WITH CSV;"
Replacing your_table and your_app with the appropriate info
Neanderslob VS Technology 
I need to change it slightly to work for me: psql `heroku config:get DATABASE_URL -a your_app_name`?ssl=true -c “\copy company_infos(email, url, created_at, updated_at) FROM ‘/Users/john/company_infos_heroku4.csv’ WITH(FORMAT csv, HEADER true);”