Update the `load_programs` command

[higs4281]

The command's s3 loading option will now be pointed at a specific bucket, validated_program_data, to ensure that raw school submissions aren't inadvertently loaded into the cfgov database without being checked.

Testing

• You should be able to run the command locally with the s3 option to load programs.

python manage.py load_programs edmc.csv --s3 true

This should return "1522 programs updated."

Review

@amymok

• [x] Project documentation has been updated (including the "Unreleased" section of the CHANGELOG)

[coveralls]

Coverage remained the same at 100.0% when pulling 0ec17637646567de706e43698a673571ce61b3b0 on load-command-update into 84f26247e0fba9a45cb44214c6e67b8ab1397347 on master.

[amymok]

👍